Large numbers of Brits have been unable to access their accounts online and withdraw cash from ATMs after separate systems problems at Lloyds Banking Group and the Co-operative Bank.
The Lloyds issue has affected Lloyds TSB, Bank of Scotland and Halifax customers this afternoon, leaving many without access to online or telephone services and unable to use ATMs or their cards in stores.
The banking giant has been using its various Twitter accounts to communicate with disgruntled customers throughout the afternoon but now says that the problem has been fixed and it is processing the backlog of transactions.
The Co-op Bank and its online unit, Smile, have also been struck by IT issues, telling its Twitter followers that: "We are currently experiencing a temporary issue with our banking systems meaning some customers have been unable to access their accounts".
Earlier this year RBS, NatWest and Ulster Bank suffered a huge IT meltdown that left some customers locked out of their accounts for days and even weeks, costing the group more than £100 million in compensation.
The scale of that problem damaged public confidence in Britain's banks and prompted the intervention of MPs, with the Treasury Committee warning the industry it had to check its IT systems to guard against further failures.