A "technical error " on the part of Barclays left a student with a £100 billion debt.
Donald Moffat from Ayrshire, Scotland, told the BBC that his current account showed two separate withdrawals of £50bn on Tuesday morning.
Moffat noticed the error after spending a night out with his wife.
"We knew we still had quite a bit left in the account as we checked last night before we went out," he said. "This morning I went out to get a few things, then, when I came back, my account was overdrawn by that amount."
The 38-year-old claimed that he had been offered £10 compensation from Barclays, but was seeking more due to the level of stress the error had caused.
A statement from the bank said: "Earlier today a technical error caused some customer accounts to be incorrectly debited.
"The problem was immediately identified and corrected within less than an hour, and all affected customer accounts are now showing correct balances.
"No customers will be financially impacted by this error. We apologise for any inconvenience this may have caused our customers."