One customer said he could see other people’s accounts totalling more than £20,000, while another reportedly discovered he had been wrongly credited with £13,000 after logging back in.
It came several hours after the bank had warned its account holders that some of its services, including online banking, making payments or transferring money, would not be possible over the weekend because of a system upgrade.
The upgrade window was scheduled between Friday at 4pm and Sunday at 6pm.
However, a message on the TSB website on Monday morning said there were still intermittent issues with its services, while a number of customers reported they were still unable to access their money.
The bank said it was working as hard and as fast as we can to get these up and running.
TSB’s social media team faced a stream of complaints from customers on Sunday evening, including several who said they could see other people’s accounts after logging back in.
Craig Malcom tweeted @TSB I currently have access to #20k+ of other peoples money.
I suggest somebody answers the phones as iv been on hold for 45 minuets!
This is a MASSIVE breach of data protection! If i have access to their account they could have to mine as well!
Another Twitter user called Bex said @TSB so go to my app and have someone else’s accounts there!!!! Serious dpa (Data Protection Act) breach! Want to speak to someone now and a half an hour wait!! What would the FCA (Financial Conduct Authority) say about this!!! Might just inform them a bank is giving away other people’s account numbers.
Laim McKenzie, from Paisley in Scotland, told the BBC My balance, because of my overdraft, is in minus, but my balance was showing at £13,000.
News Source SkyNews