help with electric and gas pleas

mike1975_2

hi all
dont know if this it the right place to post this?
a few years ago fix`d my price with a major energy supplier untill 2010
then a year or so after i fixed the price came up with a figure of money they said i owed them i think it was in the regon of £350 - £400 they wanted it there and then i said i couldnt afford it so they put in a prepayment meter the figure is now gone and paid off within 6 months of the meter going in, i did not think we were using that much gas anyway, and then after all this had gone and clear`d away this morning i receive a letter saying i now owe £90 on my electric? i rang them up to confirm they say i havent paid my bill but we have receipts from the paypoint we use? im getting fed up with all this so i said i wanted to pay it off and move to another company and have both of the energy bils on a meter, they then said i would have to pay a cancelation fee up to the date of the term, so they wanted to charge me the difference between the fixed price and the current price times the energy used at the present rate till the end of 2010, now im no maths teacher but i can see it beeing about another few £100`s, just wanted to know if anyone else had had this kind of problem? or if there is a way around it? or if i can demand they install a prepayment meters at the same rate as there 2010 rate seeing as there would be a zero balance on the acounts?

thanks