Nearly one third of card fraud victims have been forced to wait weeks or even months to get their cash back, despite obligations on banks to refund them immediately, a consumer group has found.
Some 29% of Which? members who had suffered credit or debit card fraud said they had experienced delays getting a refund.
Barclays and Barclaycard customers were the least likely to be reimbursed straight away, with nearly four in 10 (39%) of card fraud victims having to wait longer than a week to get their cash back.
One in 12 Barclays/Barclaycard customers who fell victim to card fraud had to wait between two and six months before they received a refund, Which? found.
Even First Direct, which came out best in the survey, delayed refunds to 17% of customers, Which? said.
Some 98% of fraud victims surveyed eventually got their money back, suggesting that the overwhelming majority of cases were valid.
Under the Payment Services Directive, if someone is a victim of fraud, the bank must refund them immediately unless it has good grounds to suspect that the cardholder has been negligent or acted fraudulently.
Which? executive director Richard Lloyd said: "Our research shows that banks are too often failing to refund customers immediately when they have been victims of fraud.
"With £340 million lost to card fraud a year, there are large sums at stake that can leave people seriously out of pocket and unable to pay essential bills."
Mr Lloyd said that banks should be doing everything they can to help people who fall victim to fraud "through no fault of their own".