Customers took to Twitter to vent their anger after many were unable to withdraw cash or transfer money online.
NatWest customer Mark Hillman had planned an evening out last night, but it was cut short when he was unable to withdraw any cash.
He said: "I went from a night out to staying in, because I couldn't get my hands on my cash."
More top news
Neil and Helen Robinson have been deaf since birth but after having cochlear implants fitted they can now hear.
Ian Brady has been refused permission to launch a High Court fight for the right to have his choice of lawyer at a tribunal
More than a thousand little chicks found dumped in a field near Peterborough have been put down over fears of avian flu.