Barclaycard customers have been warned to check through their post and not bin any letters with the banking firm paying back  up to £300.

Cheques are being sent in the post to compensate customers who were incorrectly charged default fees and interest while on repayment plans.

The payouts are being received by current and former credit card customers who were on the repayment plan in the “few years” leading up to 2018.

The refunds are “mysterious” and details on exactly who is eligible are “scant”, a MoneySavingExpert said.

Why is Barclaycard making these payouts?

The payouts are a result of a review by Barclaycard, the money website explained.

The review showed customers that had fallen short on their repayment plans had been incorrectly charged default fees and interest.

A spokesperson from Barclaycard told The Mirror that an “operational issue” is to blame for the error.

How much money are customers receiving?

A spokesperson said the average payout for customers is around £70.

However, MoneySavingExpert says it has heard people have received as much as £300.

The reader said: “Head’s up. If anyone ever had a Barclaycard, even if it was years ago. Don’t throw any post away, thinking it’s junk. Open it. We nearly binned ours.

“It had a cheque for over £300, due to operational procedures, default fees and interest charged incorrectly.”

Are you due money?

Barclaycard hasn’t confirmed how many people have been affected or how many payouts it is making.

However, if you are due money back the lender should write to you “in due course” by post or email - make sure the correct contact details have been provided.

You can check your contact details by logging into your online banking via the app or website, then selecting “your contact details”.

Or you can ring the customer service number on 0800 151 0900 to see what details they currently have for you.

How you will be refunded depends on if you are still a Barclaycard customer and whether you already owe money.

If you still have a Barclaycard, and you have an account balance or zero, or you are no longer with them, then it is likely you will receive a cheque in the post or an electronic payment transfer.

But if you have a Barclaycard that still needs to be paid off, then you are likely to receive a direct refund on the account to decrease the card balance.

What have Barclaycard said?

A spokesperson told The Mirror: “Following a recent review, Barclaycard is returning relevant interest and fees to some customers who had taken out a repayment plan after falling behind on repayments.

“We apologise unreservedly to those customers for not providing the level of service we should have, and we are contacting them to explain the refund they will receive.”

The spokesperson added: “We have taken, and continue to take, significant steps to review and improve our systems, processes and training to ensure we provide the excellent service our customers rightly expect.”