A technical snafu at Barclays shut down the bank's Internet, ATM, and card payments network for more than two hours on Thursday night, fuelling a wave of customer anger on Twitter.
Customers took to the micro-blogging site to vent their fury at the lock-out and pilloried Barclays for failing to provide any information about the problems.
The cause was taken up by money savings expert Martin Lewis who urged his 206,000 Twitter followers to share their experiences using the hashtag #barclaysglitch.
With the popular revolt growing, Barclays quickly got with the programme, adopting the hashtag to update customers.
The breakdown in service was an acute embarrassment for Barclays, coming hard on the heels of a presentation by chief executive Antony Jenkins, in which he hinted at the prospect of a significant branch closure programme and tens of thousands of redundancies as the bank moved more of its service online.