Re: Being made to pay someone elses electricity bill
They have absolutely no right to charge you for power used prior to you moving into your home. That is almost similar to theft by false pretences. Send them a recorded or registered letter stating that you do not accept responsibility for power used prior to moving into the premises and it is not up to you to find out who the previous occupier is as to get this info may involve someone breaking the Data Protection Act.
At the same time start looking for a new supplier as obviously you can't trust the current supplier who are only interested in ripping you off. EDF have a good deal on electric at present and Eribco on gas. We change suppliers about twice a year and save a lot of money. BTW make sure that the meter serial number is the same one against the one on their bill and keep a note of this meter serial number.