NatWest and RBS are still struggling to overcome a major meltdown of online banking system this morning, with branches opening early to deal with cash-less customers.

The bank has sorted out techical issues which hit many customers yesterday, but problems persisted this morning with the organisation admitting on Twitter that the failure was “an unacceptable inconvenience for our customers for which we apologise.”

In a sign of the changing nature of banking, RBS urged customers whose accounts were frozen to use its mobile apps to generate a secure temporary PIN number for use in its cash machines.

The application generates a secure cash code that allows users to withdraw from £10 to £100 cash and is valid for three hours and can be used at any RBS, NatWest or Tesco cash machine.

The code can be used by the person downloading it or texted to someone else.

In a bid to help customers without smartphones, the bank it announced that 1,000 NatWest branches in all major towns and cities will be open until 7pm tonight.