Three UK

Mobile network operator. Products & services: Mobile, Broadband.

Updated: 3 August 2026

Company Overview

Industry: Telecoms (mobile and home broadband)
Parent company: VodafoneThree joint venture (51% Vodafone Group, 49% CK Hutchison) since 31 May 2025
Regulator: Ofcom
Ombudsman: CISAS (Communication & Internet Services Adjudication Scheme, run by CEDR)
Customers: Part of VodafoneThree, which serves more than 27 million customers (combined Vodafone + Three)
Founded: Three brand launched 2003; Hutchison 3G UK Limited incorporated 29 November 1999
Legal entity: Hutchison 3G UK Limited (company no. 03885486)

1(industry average 3; joint-lowest with EE and Tesco Mobile)Pay-monthly mobile complaints per 100,000

What customers complain about

Customers most often complain to Three about billing and mid-contract price rises, network coverage and service faults, and problems switching provider or ending a contract. In Ofcom's Q4 2025 data (published 11 May 2026) Three was among the best pay-monthly mobile providers, with just 1 complaint per 100,000 customers against an industry average of 3, and was not separately ranked for broadband, landline or pay-TV. To complain, contact Three first: live chat, 333 from a Three phone or 0333 338 1001 from another line, the online complaints form, or by post to Three Customer Complaints, Hutchison 3G UK Ltd, PO Box 333, Glasgow G2 9AG. Three answers most complaints within seven working days. If it cannot resolve your complaint within six weeks, or issues a deadlock letter, you can escalate free to CISAS — the adjudication scheme Three uses instead of the Communications Ombudsman.

Complaint categories

1
Billing, payments and mid-contract price rises
Complaints about charges, disputed bills and annual mid-contract price increases. From 17 January 2025 Ofcom banned inflation-linked, percentage-based mid-contract rises for new contracts, so newer Three contracts must state any annual increase as a fixed pounds-and-pence amount at sign-up.
Billing/payment is a standard Ofcom complaint category; Ofcom noted the rise in Q4 2025 pay-monthly mobile complaints was mainly driven by mid-contract price increases across providers (reported, category-level, not a Three-specific published share).
2
Network coverage and service faults
Loss of mobile signal, dropped calls, mobile-data problems and home-broadband faults — heightened for Three customers by the UK-wide voice-service outage on 25 June 2025 that also affected 999 access.
Ofcom investigation opened 15 December 2025 into Three's 25 June 2025 outage; faults/service is a standard Ofcom complaint category.
3
Switching provider and ending a contract
Problems moving to or from Three, or leaving at the end of a contract — including charges after leaving or difficulties with the switching process.
Switching/contract issues are a standard Ofcom complaint category; specific Three shares are not separately published (reported, category-level).
4
Complaint handling itself
Dissatisfaction with how a complaint was dealt with — delays or having to chase. Three's own standard is to answer most complaints within seven working days, so slippage against that is a common source of frustration.
Three Complaints Code of Practice / how-to-complain page (seven-working-day service standard); complaint handling is a standard Ofcom complaint category.

Contact methods

Complaint journey

1
Contact Three first
Raise the complaint directly with Three by live chat, phone, online form or post.
Typical responseSame day
What happens
Three's code of practice asks you to contact it before anything else. Use live chat (08:00–22:00 Mon–Fri, 09:00–20:00 weekends), call 333 from a Three phone or 0333 338 1001 from another line (mobile broadband 500 / 0333 338 1003; business 337 / 0333 338 1004), complete the online complaints form at three.co.uk/support/complaints/complaints-form, or write to Three Customer Complaints, Hutchison 3G UK Ltd, PO Box 333, Glasgow G2 9AG. Three does not publish a dedicated complaints email.
2
Give Three full details
Set out the problem, your account details and the resolution you want.
Typical responseVaries
What happens
Include your name, Three account number and the mobile or broadband number affected, a clear description of the complaint, the resolution you want, and a daytime contact number. Do not send passwords, security answers or full payment details. Keep live-chat transcripts and reference numbers for any calls.
3
Three investigates and responds
Three reviews the complaint and works towards a resolution.
Typical responseMost within 7 working days
What happens
Three says it answers most complaints within seven working days, though it notes some cases take longer. If your complaint concerns a qualifying broadband/landline fault, delayed installation or missed engineer appointment, Ofcom's automatic-compensation rules may apply. If Three cannot resolve the matter, it should issue a final response or a deadlock letter explaining your right to go to CISAS.
4
Escalate to CISAS
If unresolved after six weeks or on a deadlock letter, take the complaint to the free independent adjudicator.
Typical response6 weeks or deadlock
What happens
If Three has not resolved your complaint within six weeks (reduced from eight weeks for complaints raised on or after 8 April 2026), or it issues a deadlock letter sooner, you can refer the dispute free of charge to CISAS — the Communication & Internet Services Adjudication Scheme run by CEDR (100 St Paul's Churchyard, London EC4M 8BU; 020 7536 6000; cisas@cedr.com; apply at cedr.com/consumer/cisas). CISAS is Ofcom-approved and independent of Three; Three pays the case fees, and the adjudicator's decision is binding on Three if you accept it.

Response times

Three does not publish a fixed acknowledgement or final-response deadline in the way FCA-regulated firms do. Its complaints guidance states it answers most complaints within seven working days, while noting some cases take longer. Independent escalation to CISAS is available once Three has had six weeks to resolve the complaint (reduced from eight weeks for complaints raised on or after 8 April 2026 under Ofcom's rule change) or once Three issues a deadlock letter. Three provides different complaint phone lines for personal, mobile-broadband and business customers, but the same seven-working-day standard and code of practice apply across them.

If your complaint isn’t resolved

If Three UK can’t put things right, you can escalate — free of charge — to an independent body:

Communications Ombudsman

Recent news

15 December 2025
Ofcom opened an investigation into Three (and, separately, BT/EE) over major mobile outages, after Three notified it of an incident that caused a UK-wide disruption to voice/call services on 25 June 2025, including customers' ability to contact the 999 emergency services. Three attributed the disruption to an exceptional traffic spike triggered by a third-party software configuration change.
Read more
31 May 2025
The merger of Vodafone UK and Three UK completed, forming the VodafoneThree joint venture (51% Vodafone, 49% CK Hutchison) after the CMA cleared the deal subject to conditions including a three-year cap on selected tariffs and an £11bn 5G network-investment commitment. The combined business serves more than 27 million customers.
Read more
17 January 2025
Ofcom's ban on inflation-linked, percentage-based mid-contract price rises took effect for new broadband and mobile contracts. Providers including Three must now state any annual increase as a fixed pounds-and-pence amount at sign-up.
Read more

Know your rights

Consumer Rights Act 2015
Three's services must be provided with reasonable care and skill and match what was described. If a service is faulty or not as promised you can seek a repeat performance or a price reduction. This is general information, not legal advice for your situation.
Ofcom General Conditions and automatic-compensation scheme
As a regulated communications provider Three must follow Ofcom's General Conditions, including rules on complaint handling, contract transparency and, where applicable, automatic compensation for delayed installations, total loss of service not fixed in time, and missed engineer appointments.
Communications Act 2003 (ADR)
The Communications Act requires providers such as Three to belong to an Ofcom-approved ADR scheme. Three's scheme is CISAS, giving you a free, independent route to resolve a dispute once Three has had six weeks or issued a deadlock letter.

Frequently asked questions

Which ombudsman or adjudication scheme handles Three complaints?

Three uses CISAS — the Communication & Internet Services Adjudication Scheme, run by CEDR — not the Communications Ombudsman used by BT and EE. You apply free at cedr.com/consumer/cisas (020 7536 6000; cisas@cedr.com) once Three has had six weeks or issued a deadlock letter.

How long before I can take my Three complaint to CISAS?

Six weeks. If Three has not resolved your complaint within six weeks, or issues a deadlock letter sooner, you can refer it free to CISAS. This window was reduced from eight weeks for complaints raised on or after 8 April 2026 under an Ofcom rule change.

How do I contact Three to complain?

Contact Three first: use live chat, call 333 from a Three phone or 0333 338 1001 from another line (mobile broadband 500 / 0333 338 1003; business 337 / 0333 338 1004), complete the online complaints form, or write to Three Customer Complaints, Hutchison 3G UK Ltd, PO Box 333, Glasgow G2 9AG. Three does not publish a dedicated complaints email.

How quickly does Three respond to complaints?

Three says it answers most complaints within seven working days, though it notes some cases take longer. It does not publish a formal acknowledgement deadline; the fixed milestone is the six-week point at which you can escalate to CISAS.

Is Three better or worse than other networks for complaints?

For mobile, better than most. In Ofcom's Q4 2025 data Three recorded just 1 complaint per 100,000 pay-monthly mobile customers — joint-lowest with EE and Tesco Mobile, against a 3 industry average. Three was not separately ranked for broadband, landline or pay-TV that quarter.

Does the Vodafone merger change how I complain to Three?

Not the process. Since 31 May 2025 Three is part of VodafoneThree, but complaints are still handled by Hutchison 3G UK Limited under the Three brand, its own code of practice, and CISAS as the ADR scheme.

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