Sorry to go off thread a bit but I just got this from British Gas -
“The prime minister recently announced the Government Energy Price Guarantee – meaning that from 1st October, the cost of energy for the average home will be no more than £2,500 a year for the next two years. However, your bill could be higher or lower depending on the size of your home, how many people live there and how much energy you use.”
So that’s clear then.

Basically they are capping the price per kwh to 34p - not the overall yearly cost.
An 'average' house consumes 3700 kwh per year

so if your a four bedroom then that will probably be at least double that....
A year ago you were paying about 18p kwh.
Come December, the expected price per kwh was 54p