In the letter, Barclaycard wrote: “We’ve recently reviewed the way we set some of our customers’ credit limits and can see that the limit we gave you previously may have been higher than it should have been at that time.

“We are sorry this happened and recognise that this may have had an impact on your circumstances, or you may have incurred losses.”

Barclaycard lists a number for customers to call if they want to discuss the matter further.

According to the Debt Camel website, a large limit isn’t good if you then struggle to make the minimum payments. By paying the minimum amount, the debt amount and term is extended.

And according to regulator, the Financial Conduct Authority (FCA), lenders should make sure a higher credit limit is “affordable” before they increase it.

Sara Williams, founder of Debt Camel, said if customers are happy with their cards and don’t feel making the minimum payments has been difficult, there’s no need to call.  Barclaycard will not cut your limit.

“But if paying your Barclaycard has become very hard as the limit is too high and the balance never seems to drop, you can call them and ask them to help you,” she said.

Williams said that where a customer agrees their credit limit was too high, it may be worth explaining the situation and giving examples where perhaps you’ve been unable to pay other bills or detailing your financial concerns.

She added that customers could also say that Barclaycard should have known they were facing difficulty such as by looking at their credit record, only paying the minimum or because of evident gambling issues.

Williams said: “You can then ask them to put right the problem they have caused. For example give you a refund of the interest you have been charged after they increased the limit or agree to freeze interest so your payments start clearing the debt much faster.

“But say this shouldn’t show as a payment arrangement on your credit record as it is Barclaycard’s fault the balance is too high.”

A Barclaycard spokesperson, said: “An internal review of our operating procedures for credit card limits highlighted that we did not always meet the expected standards for assessing a customer’s situation, meaning that not all of the customer’s circumstances and/or finances may have been considered as part of their application. As such, in a small minority of cases, a limit was set that may have been higher than it should have been at the time.

“In order to put things right, we have written to the vast majority of these customers to apologise for what has happened and to give them the opportunity to let us know whether they feel their credit limit has had a negative impact on their circumstances, or whether they incurred any losses. These customers are invited to contact us directly, and we will assess each case on an individual basis.”