Complain to your energy supplier first. If it’s not resolved within 8
weeks, or you get a “deadlock” letter, you can take it to the free Energy
Ombudsman, whose decision is binding on the supplier.

Making the complaint count

Put your complaint in writing, keep records, and say what outcome you want.
Note that Ofgem, the regulator, doesn’t handle individual complaints — that’s
the Energy Ombudsman’s job. If you’ve been landed with a large catch-up bill,
remember the back-billing rule: suppliers can’t charge for energy used more
than 12 months ago due to their error.

Learn more

See
suppliers, bills and meters
and our Ofgem page.

Sources

Energy Ombudsman (8-week and deadlock process); Ofgem (back billing).
Reviewed: 3 September 2026.