Utilities are different from council tax and HMRC, because there is, in most cases, an actual contract. You signed up for the supply, you took the meter readings, you paid the bills, and there is a clear exchange of goods for money. That is a real commercial relationship, and the lawful position respects real contracts.
The point of this lesson is not to teach you how to refuse to pay your gas bill. It is to teach you how to read your contracts properly so that you are paying on terms you have actually agreed to, and not on terms slipped in by the supplier without your consent.
What to look for
Open your most recent supplier letter. Look at the name on the account. Is it in capitals? Most are. That is the legal person, not you. Look at the terms and conditions. Most include unilateral clauses: the supplier reserves the right to change the price, the standing charge, the unit rate, the contract length, with notice. That is not a contract in the lawful sense. It is an open licence for one party to alter the deal whenever it likes.
You can write to the supplier setting out your understanding: that you accept the supply on the original terms, that any unilateral change is an offer of new terms, and that continued supply at the new price is conditional on your express acceptance. If they raise the price without your acceptance, you continue to pay the original rate, and the difference becomes a disputed sum.
Rolling contracts and silent renewal
Many suppliers convert a fixed-term contract into a rolling monthly contract at the end of the term, often at higher prices. Silent renewal is the standard tactic. Conditional acceptance applies here too: you accept the renewed contract on condition that the new terms are presented in a separate signed agreement, not deemed to be agreed by your continued use of the service.
Hold the line
A real supply, given and accepted, is owed for. Do not confuse the lawful refusal of statutory imposition with the refusal of a real bill for goods consumed. Pay for what you have actually used at the rate you actually agreed. The fight is over imposed extras, not over the supply itself.
Suppliers who push back will sometimes threaten disconnection. In practice, energy suppliers in Britain rarely disconnect domestic households, and the process for doing so is slow and visible. You have time to write the sequence, build the record, and switch supplier if needed.