Scottish power pre payment overcharged. Help?

Tonos

I contacted Scottish Power last week as I had noticed my top-ups weren't lasting as long as expected.
They told me that I was being charged £15 per week for a debt of over £1000 that I don't owe. They agreed that I didn't owe them anything but couldn't explain why this had happened.
£15 p/w does not sound like much, but I've been on JSA since September and struggle to make ends meet as things would normally stand.
I have been borrowing money off friends and family since October when the problem started.
Anyway, Scottish Power have now told me that I need to continue paying the extra money for 3-6 more top-ups!
I don't understand why they can't sort this out immediately by resetting my key.
Furthermore, they have told me when I stop being overcharged I would only be entitled to credit on my account. Not a cheque payment! Surely if you pay towards something you're not liable for then you're entitled to a refund? Since October I have paid in the region of £150 more, and it would be better if I was reimbursed. That way I can pay off all the small debts I owe to friends and family.
Should I phone them back and insist that this is sorted? Should I insist on a refund by means of cheque?

Thanks, Tonos.

[Deleted User]

You can see what debt is on the meter, and the weekly repayment by inserting key and going to screens "S " and "T ". They will show the total debt and weekly repay. Screen A also shows credit and debt but are nothing to do with added debts. Usually a debt from a former tenant is the cause of these mess ups. As you say, its an easy thing for them to reset the meter automatically on next top up. Its happening all the time with prepay meters

spiro

The number of top ups to reset your meter depends on a number of things, amount of time it takes to get command to the shop, you always using the same shop or not. The best thing to do is top up the minimum every day or two.