Banks have been blasted for "victim blaming" customers fleeced by fraudsters.
They have been holding many account-holders responsible for their losses after falling foul of sophisticated money transfer scams.
Banks partially or fully blamed customers only 77% of cases and delayed payouts if victims were not at fault, research found.
Watchdog Which? is now calling on banks to pay up instead of grilling customers cheated out of money.
It said it was too easy for them to wriggle out of responsibilities. And it demanded transparency over what steps are in place to prevent fraud and reimbursement rates.
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The consumer champion also called for the official Payment Systems Regulator to make banks pay when customers have been cheated into moving cash to crooks claiming to be from the bank.
One man who lost £2,000 to fraudsters claiming to be from the tax office struggled to get his cash back from his bank until the Financial Ombudsman Service intervened and ordered HSBC to pay up.
HSBC had argued the customer should have seen the warning signs before making the transfer.
The FOS said his professional background did not make him "an expert in the UK tax system".
© Getty Images/Tetra images RFScammers target older citizens (stock image)
It told the bank to refund the customer fully, doubling the partial reimbursement the bank initially offered. It said it needed to be more realistic when understanding the level of checks and diligence customers take when hit by a scam.
Gareth Shaw, head of money at Which?, said: "This latest damning evidence suggests victim blaming is simply the norm for some banks when it comes to scams.
"A voluntary code is not enough to protect victims who can lose life-changing sums of money."
He believes there has to be compulsory standards of consumer protection and strong enforcement to ensure people are treated fairly and consistently.
HSBC said: "Protecting customers from fraud is an absolute priority for us.
"We review every scam case in line with guidance set out in the code to determine whether a customer has done enough to protect themselves from being a victim.
"We act with empathy and understanding when investigating a case."
'I lost £2.5k in 'BT' fraud'
A retired teacher was left unable to buy food after being tricked into transferring her bank balance and overdraft facility totalling £2,500.
Janet Blakeley, 68 - pictured above - was taken in by scammers claiming to be from BT, saying she should move her money as her account was "compromised".
After checking online that the caller's number was correct she did as they said. Nearly four weeks on Halifax, her bank for over 40 years, has not refunded the cash she lost.
It said it fully investigates each case, including "whether the customer took reasonable steps to protect themselves".
It had a "great deal of sympathy" for Ms Blakeley and would review her claim again.
BT will "never call or email to ask for personal information including bank details unexpectedly", it said.