Scottish Power.

Ring them back to make sure it is not a scam as no doubt if it is they will be wanting your bank details.
Sorry I can't help with any other advice.

It's a scam, like tiggypiro said. They would not phone you up. You would get a letter through the post.
Anyway, I thought that people on prepayment meters are owed lots of money by the energy companies as they have been overcharging for years.
There might be something about it on moneysupermarket.

Ring them back. Tell them that you left on 7th October and left card in a credit balance. Tell them categorically that you owe them nothing. Tell them if you hear any more from them about this you will contact the Ombusman service forEnergy. (these people)

Scottish Power are notoriously bad at their accounting. You my have to shout. (I did. It worked.)

I agree, they would not ring you up and on a Sunday? You would receive a letter through the post. Refuse to speak to anybody over the phone- say that you want it in writing.

The phone call was on Friday, I've just been stewing over it until now. I have dug out my old statements so will look through them but from what I can see, one one the payments exactly cover the amount of gas used??? very strange and on the other it says I owe £41.40. How this can be on a pre-paid meter is beyond me. I could e mail them but I don't want them to know my e mail address. Maybe they phoned because they don't have my forwarding address, only my old one which I am no longer at?

My advice is to take the paper work to the CAB and ask them to contact the company. When I was an adviser, I found that a phone call, followed up with a letter - faxed if possible - was effective. A phone call on its own can be ignored, but if the matter is put in writing, they have to take notice.

Another good reason to go to CAB is that they have a fair pay for repay campaign on at the moment, because people on prepayment meters have a raw deal.