Just weeks after the disastrous tech problems that hit millions of customers at the bank and its sisters RBS and Ulster Bank, NatWest has confirmed the new problem on Twitter:
Online banking services have been hit as well as ATM withdrawals using NatWest debit cards although POS transactions appear to be unaffected.
Separately, Nationwide - which boasted that it experienced a surge in new customers off the back off the original NatWest/RBS meltdown - says that "human error" means that card transactions affecting more than 700,000 customers made on Tuesday were taken again on Wednesday.
The bank is promising to correct balances overnight and refund any related charges and, as best practice now dictates, has taken to Twitter for a PR blitz in an effort to mollify disgruntled customers, many of whom were pushed into the red by the error.
Update: By Friday morning, NatWest claimed that its online banking services and debit card transactions were back to normal while Nationwide said that customers who had payments debited twice had been reimbursed.