Black Friday has turned into a nightmare for NatWest customers after the bank’s online and mobile phone app went down and payments and transfers failed on one of the busiest shopping days of the year.

Many of the bank’s customers were unable to access their money over the phone app or online for most of the day, and transfers between accounts vanished.

The bank told customers: “We are currently experiencing intermittent issues with our Anytime Banking service, our Mobile app and Bankline including delays in processing some payments and transfers.” Later in the day it said online services had been restored, but app issues remained.

The IT glitch provoked a furious backlash from customers who claimed the bank had ruined their Black Friday spending plans, and left them unable to access funds on what for millions of people is the monthly payday.

Shoppers are expected to spend £4.3bn over the 12-day Black Friday period to Monday 2 December, up more than 2% on last year with much of that spent online. On Friday, Barclaycard said it had seen a 9% rise in transactions per second during the peak period of trading between 1pm and 2pm, with card payments running at 1,184 per second.

Some shopping centres also said they had been busy. This year, the timing of the US-inspired discount day has fallen on or after pay day for more people than it did in 2018.

Gordon McKinnon, operations director at Intu said the number of visitors to its centres around the country, which include Manchester’s Trafford Centre and Lakeside in Essex, was up nearly 13% on Black Friday last year. He said numbers were “likely boosted by the proximity to payday, and the day falling a week closer to Christmas than in previous years.”

NatWest, which is owned by Royal Bank of Scotland and has 14 million customers in England and Wales, said debit and credit card payments and cash machines were not affected by the outage. But customers reported that transfers simply disappeared – and when they tried to contact the bank, call centre lines were in meltdown.

Twitter user Zanny/Stitchy was typical of customers left bewildered when their money vanished. “I moved money from our joint account to mine, & it’s just disappeared ... the balance went down but no money appeared in my account.”

Miss Carla B said: “I need to get shopping in. What a joke ... I tried transferring the money into my mums account yep not showing…”

Another Twitter user, Adam Davies, said: “Can’t access my account on the day that I am meant to sort Christmas out. Thank you for ruining another year with your second rate services.”

NatWest pleaded with customers not to keep trying to send payments, as it could result in duplication issues. “Please do not resend any payments as we are working to get the original payment processed as soon as possible and don’t want to risk duplication of the transaction,” it said.

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The IT failure is yet another embarrassment for a bank with a long history of tech issues – a fiasco in 2012 left some customers locked out of their accounts for weeks – and came just as it was hoping to sign up for its new digital bank, Bo.

A NatWest spokesman said that as the shopping day came to a close, it was still unable to fully fix the issue. In a statement it said: “We are aware that some NatWest customers are still experiencing intermittent issues accessing our mobile and online banking. We apologise to customers for the inconvenience and are working hard to fix the problem. There is no impact on debit cards, credit cards, ATMs, telephone and branch banking services – customers can continue to use these as normal.”

In the run-up to Black Friday, NatWest said it would confidently “process over 1 million customer card transactions per hour”. But with the glitch happening during the annual shopping frenzy, it left some customers saying they would switch to rivals such as Monzo or Starling instead.