Some 29 per cent 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 four in ten card fraud victims waiting over a week to get their cash back.
One in 12 Barclaycard and Barclays 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 per cent of customers, Which? said.
Some 98 per cent of fraud victims surveyed 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 they were negligent or acted fraudulently.