If you've got a Santander credit card and you've recently paid your balance online with a debit card, check your statement now – the bank's admitted charging people twice following a technical glitch.

We've seen reports in the MSE Forum over the past week from people who have been left out of pocket – one by £1,000 – after their bills were duplicated when they paid by debit card. (See our Credit Cards guide to see if you're on the best deal.)

Santander couldn't tell us how many people have been affected by the payment glitch or exactly when it occurred. Customers who paid by direct debit or bank transfer haven't been affected.

If you paid by debit card, you may need to act to get your money and any fees back.

  • Did you use a Santander debit card? You'll automatically be refunded the duplicate payment as well as any fees or additional charges you incurred if, for instance, you went overdrawn as a result.

  • Did you use any other debit card? Contact your card issuer for a refund. If you suffered any fees or additional charges, contact Santander for a refund. See our How to Complain guide for more information.

Separately, some customers were unable to use their debit cards or withdraw cash from ATMs on Tuesday evening. This issue has since been fixed.

Online banking frustration

Angry and worried customers have vented their frustration on the MSE Forum:

  • Gravitas wrote: "I made my payment a couple of days ago and was told it had failed. I made the payment again which went through and sure enough, both lots of money have been taken. I have a credit card for my office expenses due to travelling a lot and this has resulted in me being £1,000 down. I've called to explain this leaves me in a pretty vulnerable position: overdrawn, mortgage payment bouncing, people relying on me, etc."

  • Sheff71 wrote: "I took out a credit card in early June, and paid for a Butlins family holiday with it. I was a little surprised to get a letter claiming I was over £2,000 over my credit limit and I would need to look into paying it back soon."

What does Santander say?

A Santander spokesperson says: "We are aware that some Santander credit card customers trying to pay their bills online with a debit card have experienced an intermittent error message and therefore attempted to make the payment again, duplicating the payment from their debit card.

"All refunds have been dealt with automatically; therefore all Santander customers have been refunded.

"We are expecting all non-Santander debit card customers to be refunded via the acquirer shortly – please note different banks have different timescales for applying these refunds so we cannot give a specific time as to when these will be received.

"Non-Santander debit card customers, who have subsequently gone into their overdraft and been charged additional fees, as a result of this error, should contact us to ensure they are not financially impacted.

"We want to reassure customers that all other payments remain unaffected and there is no impact on the use of credit or debit cards when shopping online."