SIX Payments Services has apologised to Swiss and Liechtenstein customers for a snafu last week which resulted in debit card transactions being booked twice.
The technical problem meant that not only were transactions from Tuesday booked on Wednesday night as planned but also for a second time the following night.
However, SIX says that no payments were executed twice, meaning that there were no duplicate cash flows and that no customers suffered any losses.
The affected banks have already reversed 99.93% of the double bookings, with the remaining 0.07% set to be fixed over the next few days.
SIX has not revealed how many payments were affected but the firm processes around 1.4 million transactions involving Swiss and Liechtenstein debit cards a day.