Tom Gerken
Technology reporter
Getty Images
NatWest customers have been venting their frustration as the bank's mobile app continues to be inaccessible, leaving some unable to access their accounts.
They have reported problems including being unable to make purchases or pay staff.
NatWest said on Friday it was working as "quickly as possible" to find a fix - but the app was still down late into the afternoon.
The firm has apologised and says its web-based online banking service is still working normally.
However, a number of customers have contacted the BBC to dispute this. BBC News has contacted Nat West for comment on their claims.
Problems began to be reported on outage-checking site Downdetector at 0910 GMT.
BBC/NatWest
People saw this message when trying to use online banking on Friday
Since then, customers have taken to social media to complain about the impact the IT failure is having on them.
One person said they had to "put back my shopping because of it", while another said they were "waiting to go shopping" but couldn't transfer money to do so.
NatWest has advised customers on social media that it has "no timeframe" for a fix, but said its team is "working hard" to resolve it.
Customers are being advised to access their accounts in other ways if they can - such as through online banking.
However, some people have reported problems with NatWest's online service too, with one sharing an error message which they said was displayed when they tried to make a payment.
Others have expressed frustration with the bank's response, with one saying it was "disgraceful" there was no timeframe, while another called it "very poor service".
"What I don't get is the bank closes loads of branches 'to save money' and forcing people to rely on the app and online banking... but clearly hasn't invested in a system that works properly," one angry customer said.
A recurring problem
This is the latest in a long line of banking outages.
In May, a number of major banks disclosed that 1.2m people were affected by them in the UK in 2024.
According to a report in March, nine major banks and building societies have had around 803 hours - the equivalent of 33 days - of tech outages since 2023.
Inconvenient for customers, outages come at a cost to the banks, too.
The Commons Treasury Committee found Barclays could face compensation payments of £12.5m over outages since 2023.
Over the same period, Natwest has paid £348,000, HSBC has paid £232,697, and Lloyds has paid £160,000.
Other banks have paid smaller sums.