The CEO of TSB Bank has blamed an HP server failure for the meltdown which left Lloyds Banking Group customers unable to use debit cards and cash machines for several hours yesterday.
The problem at the part state-owned group affected Lloyds, Bank of Scotland, Halifax and TSB customers between around 3:00pm and 7:30pm yesterday afternoon.
A minority of transactions at the point-of-sale failed to go through, while around half of the group's 7000 ATMs suffered problems. Credit cards and online and phone banking services were unaffected.
The group has begun an investigation into the issue but TSB CEO Paul Pester has used Twitter to provide a disgruntled customer with an update:
A group spokeswoman later told the BBC: "We are working with our suppliers to understand what caused the hardware failure, but there is no evidence that it was as a result of an external intervention or attack on our systems.
"We continually review and update our systems as necessary and make significant investment to do this."
There have been several high-profile tech meltdowns at UK banks in the last year, with RBS chief Ross McEwan admitting last month that the group was reaping the consequences of decades of IT neglect.
A recent survey from Fujitsu suggests that such problems could prove costly to banks, with a quarter of Brits saying that they would seriously consider switching their provider if it suffered a major technology failure.