For the third time in 18 months, RBS and NatWest customers were frozen out of their accounts after payment systems crashed.
In particularly bad timing, thousands of transactions were blocked on Cyber Monday, the busiest day for online shopping.
The fault stopped customers from accessing bank statements, debit and credit card payments and online transfers and purchases.
“We are very sorry for the system issues that affected our customers. We will confirm when all systems have returned to normal service,” said an RBS spokesperson last night.
“If customers have been left out of pocket as a result of these system problems, we will put this right.”
RBS’s payment systems crashed in March of this year and in June 2012.