A Facebook post went viral after a consumer saw a £99 debit on her online bank when she bought petrol at the pump from Asda at the weekend.
The mother-of-two's complaint about £99 being taken from her was shared widely on social media.
But the money never left her account, according to the supermarket and banks.
The £99 is in effect a holding charge introduced to help cut down fraud and stop people inadvertently going into the red.
The pre-authorised amount is cancelled as soon as the correct value is paid.