NatWest customers face problems into the weekend as the bank works to clear up a backlog of chaos caused by three days of technical hitches.
The bank has taken the step of opening its doors on Sunday, saying it is working "round the clock" to put the situation right.
Angry customers have vented their frustration over the problems, which are also affecting Royal Bank of Scotland (RBS) and Ulster Bank users, with some finding payments have gone awry and others having disappearing wages, or holidays and home purchases disrupted.
It remains unclear exactly when the issues will be completely resolved and the repercussions have extended beyond the banks' own clients, with one couple who are not NatWest customers left unable to move into their new home. All three banks are part of RBS Group, which is clearing a raft of problems caused by a technical fault which it believes it has fixed.
Customers have raised concerns about getting money for the weekend, although the group has said staff in branches will help them get access to cash. NatWest are extending their opening hours to 6pm on Saturday, and those which open on Saturday will also be open on Sunday morning.
Account balances were not updated properly overnight, meaning that credit and debit payments were not showing up as quickly as they should, although RBS Group said the money is "in the system".
People going into their branch could not necessarily see the most up-to-date account information. Fears have been raised that thousands of customers could be hit with penalty charges if their regular household bill payments such as mortgage payments are affected.
The group has apologised and pledged that no one will be left out of pocket and anyone who incurs penalties because of the problems should contact their branch.
Susan Allen, customer services director for RBS-Natwest retail, told ITV News it was difficult to say exactly when all the problems would be resolved. She said they were due to "an error in our system which we believe we have now fixed but we are clearing the backlog".
NatWest has more than 7.5 million personal banking customers, but the group said it could not tell how many have been affected as it was not possible to know when they were expecting payments into their accounts. However, Ulster Bank said that about 100,000 of its customers have been affected by the same issues.