Customers of Royal Bank of Scotland have been struggling to use their cards at store checkouts and ATMs - the day after the bank was fined a total of £56 million for a huge IT meltdown in 2012.
Today's glitch affected customers of sister banks RBS, NatWest and Ulster Bank who were trying to use Visa debit and credit cards in stores and at cash machines.
A spokeswoman for the banking group said there was "minimal customer impact". Those affected were attempting to make higher-value payments or to make transactions abroad, the bank said.
The problems started at 7.45am and were resolved by 9.15am, the bank said.
However, one customer writing on NatWest's website said they had found out today a payment had not gone through properly after using their card yesterday.
The customer wrote: "Did a Tesco shop yesterday, everything went through.
"Advised this morning by Tesco that the payment did not go through."
The customer, who described the situation as "very poor", said they had been told by the bank that an issue was affecting a number of Visa debit card customers.
A statement from RBS said: "A small number of customers experienced issues early this morning while using their RBS, NatWest and Ulster Visa debit and credit cards. There was minimal customer impact and the issue was quickly resolved."
Yesterday, the bank was landed with penalties totalling £56 million by regulators over its huge systems crash in 2012, which also affected customers of RBS, NatWest and Ulster Bank.
RBS chairman Sir Philip Hampton has said that since the incident, the bank has spent hundreds of millions of pounds on increasing the resilience of its IT systems.
RBS admitted to "unacceptable weaknesses" in its computer systems as around 6.5 million customers - equivalent to 10% of the UK population - suffered disruption lasting for several weeks in some cases.
They were unable to use online banking facilities or obtain accurate account balances from ATMs. Mortgage payments were delayed and customers left without cash in foreign countries.
The issues in summer 2012 stemmed from a botched upgrade to the software that processed updates to customers' accounts overnight.
When it noticed problems with the upgrade the bank's central IT function decided to uninstall it without first testing the consequences of that action.
The bank is investigating the underlying cause of today's problems, which it said are unrelated to the meltdown of two years ago.