How can I get British gas to zero the previous tenants debt?

There's a card meter there's a debt of emergency credit around £45 . They said I have to go to a certain pay point to top up up to 5 times on different days and my card will receive a message they sent to zero the debt.ive been 8 times and it still won't work.
I was on the phone to them for ages ,they said they would phone back but haven't

katie2015-01-10T07:09:43Z

Are you using the previous occupiers card ? British Gas have to wipe any previous debt as long as you provide proof that you are the new tenants. Tell them you want a new card and someone to come out and reset the meter as it's not your debt.

grrrzippy2015-01-10T08:29:53Z

Yes I am using a new card thanks,actually this is the third new card I got as the first two wouldn't top up

Geoff B2015-01-10T11:24:17Z

British gas are known for bad customer service, all you can do is keep having a go at them