Nationwide customers are unable to send or receive money just days before Christmas.
According to the building society, there is a "delay" to the transactions - but there is no need to resend them.
However, Nationwide said that direct debits and standing orders are working as normal, and that people can continue to use their cards to pay in shops and withdraw money from ATMs.
According to the company's social media account, there is no timescale for when usual services will return.
The firm is asking people to check the service status of the system on their website.
A Nationwide spokesperson said: "Unfortunately, there is currently a delay on outbound payments reaching people's accounts as well as inbound payments reaching Nationwide current accounts.
"We are working hard to resolve the issue and apologise for any inconvenience caused.
"There is no need for people to resend payments and these will be processed as soon as possible.
"All other services are working normally, and members can continue to use their cards to pay for goods and services, access the Internet Bank and Banking App and withdraw cash from ATMs."
With Christmas in just four days, people are understandably concerned about being able to get their shopping done.
There were also concerns about people being able to receive wages - especially with some companies advancing payment to help with festive purchases.