Thanks for the response. You are right. I have written to them and await the reaction. We must pressure them or they will continue the practice as it makes them a lot of profit.It is worth saying what actually happened.
I got an email to read my meter on line. This I did and got back a bill, saying the actual would be available in three days.I then get a really nasty email saying "are you paying for the energy you use"? and stating I had not supplied a meter reading, which was a condition of the on-line account. This failure has mean't they had to estimate my bill. A second email then arrived raising my monthly direct debit by £40, based on their estimate of my useage. I reread and entered the current meter reading and received back a bill £200 less than their estimate, in one quarter. I may be cynical but 1. They state I did not enter a reading, I did. 2. They put in a high estimate and change my monthly payment substantially.This gives them use of my money over a long period. This is sharp practice.
It is my intention to use the customer perogative and change supplier.