By Paul Lewis
Presenter, BBC Radio 4's Money Box
Bank of Scotland has admitted it took the October mortgage payment from some customers three times in three days.
The bank said it worked "flat-out" to resolve the problem
It will not confirm or deny press reports that 7,000 borrowers suffered the triple payment whammy.
Some have been left thousands of pounds out-of-pocket and although the excess has now been repaid customers will have to ask for any bank charges or costs to be refunded.
Bank of Scotland said the problem had now been fixed and that compensation would be considered "on a case-by-case basis".
The problem began with payments due out in the week of 14 October.
An error in the computer tape led to the payment being taken again the next day and in many cases again the day after that.
A spokesman told BBC Radio 4's Money Box: "There was a technical error on the system which manages the payments from Bank of Scotland mortgage customers, which resulted in their monthly mortgage amount being taken either twice or three times.
"By the time the error had been identified the request for the third payment had already been actioned and could not be cancelled."
The bank said it returned all the payments by the end of Friday.
But some customers who had been left in difficulties during the week were very upset.
Nicole, who is buying her home in London, told the programme: "I'm outraged. Rather than one debit being taken from my account, three were taken on consecutive days.
"The normal payment is just under £1,300 and I am now out-of-pocket nearly £4,000 which, as you can imagine, has caused a bit of a cash-flow issue.
"I feel they ought to compensate me for this. I had to make the calls to my bank and the Bank of Scotland, so a lot of time and effort for something that's not my problem."
However, Bank of Scotland does not plan to make a blanket compensation offer, though it will reimburse any charges incurred by customers going overdrawn or missing other payments.
When customers make a mistake and go overdrawn without agreement or exceed an agreed overdraft limit, Bank of Scotland charges them £30 and then £28 for each payment that is made, and £39 for each payment that is bounced.
But bank of Scotland has no plans to pay such penalties automatically to customers for its mistake.
A spokesman said: "We have written to customers stating that no-one will be left out-of-pocket as a result of this error. We will consider compensation requests on a case-by-case basis."
BBC Radio 4's Money Box was broadcast on Saturday, 21 October 2006 at 1204 BST and will be repeated on Sunday, 22 October at 2102 BST.