We are on prepayment gas and electric (rental) and I think it costs us a fortune over winter but it's probably normal.
Last winter it was £25 a week on each. But we were cold a lot of the time. Had the heating on 2-3 hours a day and put the hot water on 3x a week for baths (with cold washes in between). It doesn't help that this house is like a sieve.) £200 pound a month to be cold just makes me want to cry.