Britain's biggest building society was forced to apologise to its customers again today after they were locked out of their accounts online for the second time this week.
The building society's mobile banking service was also unavailable tonight, but ATMs were operating as normal.
On Tuesday Nationwide apologised after an IT hitch stopped customers from accessing their accounts online.
Last July, the building society was hit by another banking error when nearly three-quarters of a million customers saw debit card payments taken from their accounts twice.
Nationwide corrected those mistakes and promised to reimburse anyone who incurred extra charges as a direct result.