[Neil]

Part of the guess is to do with you paying what is in effect the rent of the meter or the standing charge. Depending on your usage will depend how much they need to take of you for each unit used to pay the standing charge. Because the card meters and the whole way of paying with the cards costs more money the user has to pay either more for the electric/gas used or more standing charge.

I read that the Government don't think people on pre payment meters should pay more than those on direct debit for the same amount of energy. Of course they should, it is a more expensive way to pay for the electric/gas.