Santander's UK customers were unable to use the bank's cash machines and online services for over six hours yesterday after a power cut.
The bank suffered a power failure at a processing site at around 11.00am yesterday while internal testing was taking place. Customers were unable to use online services and more than 2000 ATMs during the outage, which lasted until 5.30pm.
During the outage, customers were still able to make point of sale payments and receive cash-back, says Santander
The problem affected former Abbey and Bradford & Bingley customers but not Alliance & Leicester, indicating an issue with the shared Partenon banking platform.
Unlike the other acquired units, A&L's branches and customers are not expected to be transferred to the unified Partenon platform until the fourth quarter of 2010.