I've got a letter from the company saying they can't resolve the problem

If your problem hasn't been sorted out 12 weeks after you first complained about it, or you have received a letter from the company saying the issue is deadlocked, you can take your complaint to an independent arbitrator.

OFCOM regulations advise that every telecommunications company must be a member of an Alternate Dispute Resolution scheme.

There are two schemes in place, one by the Office of Telecommunications Ombudsman (OTELO) and CISAS (Communication and Internet Services Adjudication Scheme)Both offer an independent dispute resolution service for communication providers and their customers. Find out from your company which service they are signed up to, and how to contact them.

The decision of the arbitrator is binding on the company if you accept it. You don't have to accept it - you can decide to take the matter further instead.

If you are unhappy with the outcome of the ADR ruling, or if the telecom provider is not part of one of the schemes, get in touch with the regulator, Ofcom.