Nationwide says a "fault" on Friday morning led to all payments between it and other banks and building societies being delayed.
In a service update on social media this morning, Nationwide told customers: "We're sorry, payments to and from other building societies and banks are delayed at the moment."
Transfers between Nationwide accounts, direct debits, standing orders and card payments were not affected.
By midday, the firm reported that "payments are now flowing again and any queued payments will be processed over the next few hours."
However, many customers were left unimpressed by the update.
Said one on Twitter: "Next few hours 🤔 I’m sitting here with no electricity since 9am as I still can’t pay for it yet from my account. some compensation sounds like a great idea #Nationwide"
Fumed another: "Closing my accounts with nationwide. Your absolutely useless!!!. AVOID NATIONWIDE GUYS!!!!!!"