Mistakes do happen, if your account is showing in credit this is because osmone has manually credited the account.  When you make a payment through direct debit, this is automated an has no human intervention.

If your account is showing in credit of £160 id suggest giving talktalk a call and ask them to send you a cheque out for this amount ;-) 

Before cancelling with talktalk I called to ask if, due to the fact that the screwed up my Broadband. They advised that I would not be charged.

A few month later, I received a bill through for 70 quid. I called them up outraged and to be fair they did admit it was a mistake and then credited £70 to my talktalk billing account (Even though they hadn't taken any mony from me), so then my account was £70 in credit.

A few months later I get another bill for £70 and the same thing happens. I get straight on the phone and the same thing happens. "I'm sorry Mr Macleod, we will rectify this right away." I check online and now my account is £160 in credit!

How can we expect this company to be carefull with our money when they couldn't care less about their own?