A student from Ayrshire was left in a state of shock when his online banking statement showed him to be overdrawn by almost £100bn.
Donald Moffat, 38, from Irvine, said that on Tuesday morning his Barclays account was showing two separate withdrawals of £50bn.
The bank said a "technical error" was to blame and apologised.
Mr Moffat said Barclays also offered £10 in compensation for the phone calls he had to make to resolve the error.
The full-time student, who is also a part-time care worker, e-mailed a copy of his bank statement to BBC Scotland.
It showed a debit balance on 30 December of just under £100bn.
Mr Moffat said on Tuesday morning his wife had noticed "a major discrepancy of two £50bn debits" being taken out of his account.
"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."
Mr Moffat said he had "been passed from pillar to post" after making the error known to Barclays.
He also said he was looking for the bank to up its offer of compensation for the level of stress he had been put under in trying to resolve the situation.
In a statement Barclays 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."