hiya, ive moved into a new house and it turns out even though the new gas company has set me up a direct debit, the previous people were on a prepayment meter. they say that to change it i need to run out of emergency credit. have never used a prepayment meter - i dont understand the screen. ive googled it and cant find versions of my screen. does credit count up or down? from 15 downwards or up from zero? currently it says £-1.81. does this mean i have spent 1.81 or have that left???? also, i dont know why im presuming emergency credit is fifteen quid and not a fiver or a tenner. can someone advise?