A disabled woman was fined £70 after she queued for 15 minutes to use an Asda car wash.
Danielle Tucker waited to use a self-service jet wash at the 24-hour garage on June 4 at the Asda petrol station in Northfield Avenue, Kettering, Northants.
They received a £70 fine ten days later stating they had exceeded the "grace period" for staying in the car park when the supermarket was closed.
Danielle, 43, who suffers from osteoarthritis, was offered a £30 discount if she paid within two weeks but she refused.
The care worker said: "It was about 9.45pm so the supermarket car park was pretty empty.
"They have self-service pumps so there weren't any staff there. I used the jet wash and spent about half-an-hour cleaning the car.
"It's just a given thing as the pumps are open 24/7. We went down on the off chance that the car wash was open.
"There were two girls already using it so we had to wait 15 minutes for our turn. Ten days later we received a letter saying we had been fined £70 for staying too long in the car park.
"I was shocked, I was using their service. How does that make sense. Luckily I paid on my card. When I got the letter I was p****d right off. At first I was like 'what the hell have I got that for?'
"How can you get a parking ticket when you're using a service? It was the most expensive car wash I've had."
The Asda petrol station operates a self-service pump system which lets customers pay and fill up with fuel when the supermarket is closed.
Danielle and her wife Sarah, 35, say they spent a maximum of 45 minutes on the forecourt and say a man in a BMW stayed for longer than them.
Danielle added: "It was £8. My car was absolutely filthy as it was parked up for six weeks while I was recovering. I don't know how long they actually allow you to be in there.
"There was a lad in a BMW who washed his car before we arrived and was drying when we left so he'll have one.
"I'm not going to be using it again. I'll have to go to Tesco to use their pump. They (Asda) shouldn't have the garage open or be offering services if you're not allowed to be in the car park at the time.
"If you're waiting for their services you don't expect to get a ticket. Others might have just paid it and not appealed."
Parkingeye, who monitor the carpark, say the couple exceeded the grace period for petrol station customers but have since cancelled the fine.
A spokesperson said: "The car park at Asda Kettering features prominent and highly-visible signs throughout providing information on how to use the car park responsibly.
"Asda customers have a maximum stay of three hours and the signage clearly states that there is no parking outside of the store opening hours.
"There is also a grace period for people using the petrol station and its facilities out with store hours.
"The motorist received a parking charge notice due to being within the car park for 45 minutes when the store was closed.
"However following an appeal and review of the case, we have cancelled the PCN.
"Parkingeye operates a BPA (British Parking Association) audited appeals process, which motorists can use to appeal their parking charge notice.
"If anyone has mitigating circumstances, we would encourage them to highlight this by appealing."