Computer glitches which led to chaos for HSBC customers on Bank Holiday Monday have been fixed, the High Street bank says.
Some shoppers with HSBC Switch cards found them refused
The problems meant customers were unable to get money from cash machines or use credit cards and Switch cards.
"Our payments systems and ATMs are back up and running," said HSBC on Tuesday.
However, some customers have told the BBC they are still having difficulties accessing its website - problems HSBC has blamed on a high volume of traffic.
HSBC advised people experiencing problems to log back in to their accounts.
The bank said an "internal systems problem" was behind the glitches which hit shoppers at the height of the January sales rush and on the final day of the Christmas holidays.
The gremlins were finally expunged on Monday evening, but problems with the HSBC website continued through the night.
On Monday, a spokeswoman for HSBC said the problem was the most serious the bank had experienced in its history, but dismissed speculation that hackers were responsible.
The bank said it was confident there would not be a security risk to people's accounts as a result of the problems, which were purely a technical mishap.
"There are investigations ongoing to make sure that this is doubly the case," said HSBC.
It said the problems had been widespread, but had not affected every cash dispenser or card payment outlet.
However, the banking giant advised anyone needing help as a result of Monday's problems to call its customer helpline on 08457 404 404.