I've had a similar experience to you. Plusnet took approximately £95.00 from my Bank Account at the end of April for a £7.00 bill and then had the audacity to write to me a month ago and tell me not to worry and my account would be credited the difference.
It turns out that they'd failed to bill in February and March but then overbilled in April, May and June leaving a total credit due of approximately £90.00. There was an issue with how the discount was applied to the account.
Anyway having chased for a month I was told a week ago that my Plusnet account had been credited! Well I was over-the-moon. Thank you Plusnet for holding onto money which was stolen from my Bank Account. How ever can I repay you! I insisted on a refund and was told last Monday that it would take up to 5 working days to reach my Bank Account and it has yet to arrive.
If you've paid by Direct Debit then you should be able to approach your Bank and start an Indemnity Claim on any wrongfully claimed Direct Debits. The Bank credits your account and then chases Plusnet.
I'm giving Plusnet a couple more working days and if my money isn't returned in that time then I'll be going down the indemnity route on the April Direct Debit. There are rules around Direct Debit to prevent companies acting in this manner, a manner which is simply in bad faith. I'd also suggest you raise a complaint with Ofcom. They won't investigate each individual case but if enough people report this type of behaviour they will intervene (as they have had to do with Plusnet once before).
