Customers of Natwest and Barclays have both apologised to customers who have been unable to access mobile and online banking services due to unrelated IT outages in recent days.
Natwest customers were unable to view account information or conduct transactions via mobile devices for over six hours on Sunday.
"Sorry if you had trouble getting into mobile banking between 14:47-21:08. Our service is now running as normal, thanks for your patience," the bank said via its official Twitter account.
Customers took Twitter to complain about the outage, which left many unable to make payments. One said: "@NatWest_Help time to move banks I think. once down a mistake twice a habit third time unforgivable.#NotGoodEnough."
Natwest has experienced a number of mobile and online banking outages in recent months, with thousands of customers unable to make purchases on the busiest shopping day of the year in December.
On Friday afternoon, Barclays customers were unable to withdraw funds from ATMs or access mobile and online banking for a short period of time.
"The issue affecting some transactions with Barclays has now been resolved. We apologise if you were affected and for any inconvenience," the bank said.
Nationwide Building Society customers were also unable to access account information online and through mobile devices in another outage last week.
Mobile banking has become increasingly popular as in-branch transactions continue to decline. According to to the British Bankers’ Association, the number of mobile banking transactions has increased significantly in the space of 12 months, with smartphones and tablets used for 18.6 million transactions a week during 2013, up from 9.1 million in 2012.