O2

Company Overview

What customers complain about

Complaint categories

1. 1
   Mid-contract price increases

   Ofcom attributed O2's rise to the top of the Q4 2025 pay-monthly mobile complaints table largely to customer reaction to mid-contract price increases.

   Ofcom Q4 2025 complaints report (published May 2026); ISPreview/Mobile News coverage.
2. 2
   Complaint handling

   In Ofcom's data, a leading reason customers complained about O2 was how their complaint was handled.

   Ofcom quarterly complaints reports (2025).
3. 3
   Billing and charges

   Billing disputes are a recurring category for O2; historically Ofcom fined O2 £10.5m in 2021 for a billing error that double-charged some departing customers.

   Ofcom enforcement decision, February 2021.
4. 4
   Network coverage and service problems

   Coverage, signal and service-interruption complaints are commonly reported by mobile customers; specific incident details on review platforms are reported, not verified.

   Reported theme, not verified (review platforms).

Contact methods

• O2 Pay Monthly complaints202 (free from an O2 mobile) / 0344 809 0202
• O2 Pay As You Go complaints4445 (free from an O2 mobile) / 0344 809 0222
• O2 Business complaints8002 (free from an O2 mobile) / 0800 977 7337
• O2 complaints form (online)O2's preferred first step for raising a complaint.
• O2 Complaints Review Service (post)O2 Complaints Review Service, PO Box 694, Winchester, SO23 5AP.
• CISAS (independent ADR scheme, operated by CEDR)020 7520 3814

Complaint journey

1. 1

   Raise your complaint with O2

   Contact O2 by phone, its online complaints form, or by post.

   Typical responseVaries
   What happens

   Start with O2 directly. Pay Monthly customers call 202 (free from an O2 mobile) or 0344 809 0202; Pay As You Go 4445 / 0344 809 0222; Business 8002 / 0800 977 7337. You can also use O2's online complaints form or write to O2 Complaints Review Service, PO Box 694, Winchester, SO23 5AP. Give your account number, explain the issue clearly and say what outcome you want.

2. 2

   O2 investigates

   O2 routes your complaint to the relevant team and investigates.

   Typical responseUp to 6 weeks
   What happens

   Under O2's three-stage process, once you have raised a complaint O2 directs it to the relevant team to investigate. Keep a record of your reference number and chase if you do not hear back.

3. 3

   O2 provides a resolution (or deadlock)

   O2 responds with a resolution, or issues a deadlock letter.

   Typical responseUp to 6 weeks
   What happens

   O2 responds by phone or email with its resolution. If it cannot resolve the complaint, or you remain unhappy, it can issue a deadlock letter that lets you escalate to independent adjudication straight away.

4. 4

   Escalate to CISAS (independent ADR)

   Refer an unresolved communications complaint to CISAS, O2's ADR scheme.

   Typical response6 weeks or deadlock
   What happens

   If your communications complaint is unresolved after six weeks, or you have a deadlock letter, take it to CISAS — the Communications & Internet Services Adjudication Scheme, operated by CEDR (020 7520 3814, cisas@cedr.com, 100 St Paul's Churchyard, London EC4M 8BU). CISAS is free to use and its decision is binding on O2 but not on you. You have 12 months from a deadlock letter to bring a case. Note: O2 uses CISAS, not the Communications Ombudsman.

5. 5

   Financial-services or last-resort routes

   Some complaints go to the Financial Ombudsman; Ofcom sets rules but does not settle individual disputes.

   Typical response8 weeks (financial)
   What happens

   Complaints about a financial product (such as a device credit agreement) can go to the Financial Ombudsman Service after eight weeks rather than CISAS. Ofcom regulates O2 and enforces the rules, but it does not resolve individual complaints. As a final option you can consider the small claims court.

Response times

If your complaint isn’t resolved

If O2 can’t put things right, you can escalate — free of charge — to an independent body:

• Communications Ombudsman

Recent news

• 11 May 2026

  Ofcom's Q4 2025 complaints report made O2 the most-complained-about pay-monthly mobile provider at 7 complaints per 100,000 customers, versus an industry average of 3, with mid-contract price increases cited as the main driver.

  Read more

Earlier cases

• 12 February 2021

  Historic: Ofcom fined O2 £10.5m after a billing error (running from at least 2011 to 2019) double-charged some pay-monthly customers who were leaving; over 250,000 customers were billed £40.7m in incorrect charges and around 140,000 paid £2.4m. O2 refunded affected customers in full plus 4%.

  Read more

Know your rights

• Consumer Rights Act 2015

  O2's mobile service must be provided with reasonable care and skill, and any digital content must be as described and of satisfactory quality. If it is not, you may be entitled to a repeat performance or a price reduction. This is general information, not legal advice.

• Ofcom General Conditions of Entitlement

  As a regulated provider O2 must operate a clear complaints procedure, belong to an Ofcom-approved ADR scheme (CISAS), and signpost ADR after six weeks or on deadlock. Rules also require transparency around contract terms and price changes. This is general information, not legal advice.

Frequently asked questions