Ticket holders for Horsham car parks had to double-take after the barrier machine indicated they had in excess of 600 days’ free parking.
Customers at the Forum and Swan Walk car park described scenes of chaos as they tried to get into work in the past few days.
One commuter who uses the Forum in Black Horse Way said her ticket - valid for 20 days - apparently had 634 days on it when she entered the car park last week.
The following morning those days were dramatically slashed to just 12.
But that evening the card was swallowed by the machine and branded invalid.
She told the County Times: “I was surprised to see the ticket as having more than 600 days but I assumed it was a blip on the screen.
“Eventually it did revert back to what I thought was the correct amount of days but then it took the card and said it was invalid.”
She added: “It’s caused me some confusion and presumably a lot of other people as well.”
The glitch has led to cards being swallowed unexpectedly and has been an ongoing issue throughout April.
Horsham District Council says it is working to fix the problem.
A spokesperson for the local authority said: “The council is aware that there have been some technical issues with the parking machines and staff are looking into this.”
A five-day ticket for access to the Forum car park is £17.50, compared to £25.00 at Swan Walk.