Margaret Wilcock, 63, was taking severely disabled foster son Michael Hendry to an appointment at a Garstang dentists with carer Alison Morley when a warden at the Community Centre car park issued a ticket to her specially adapted disabled access van.
Margaret says the warden even watched as she and Alison struggled to get 15-year-old Michael out of the vehicle when they first arrived in the pouring rain.
But after The Courier inquiries Wyre Borough Council has agreed to scrap the fine, has apologised to Margaret and also promised to investigate allegations about the warden's behaviour.
Margaret, who has been fostering for 40 years and has looked after 30 children, said: "Michael had been too ill to go to the dentist and we kept having to cancel it and re-arrange. He hadn't been too well the night before and we have to be so careful with him. He hasn't to get too cold.
"It was pouring when we got to the car park but I told Alison to make sure the permit was on the dashboard and the right time was on the clock.
"We saw the traffic warden standing outside the dentists, and he watched us as we got out of the car. We were only gone 25 minutes and when we got back we found the ticket saying the permit hadn't been displayed properly."
Margaret added that a passer-by even told them the warden had boasted about how he was going to give them a ticket because the permit was upside down.
Michael has severe brain damage and epilepsy. He can't communicate and is fed through a tube in his stomach. His permit is two-sided, with photo and date of birth on the back, but Margaret and Alison didn't realise it had to be a certain way up.
Alison said: "Anyone could see it was a legitimate permit. The warden would have seen it was a case of just putting it the wrong way round.
"He's obviously got a job to do, but it seems so petty when he stood there and watched us.''
Margaret added: "Police move on people who park on the High Street and block the traffic. They don't give them a ticket. And yet someone who parks legally gets a fine. It's not about the money, it's about the principle."
Contacted by the Courier a Wyre Council spokesman said they would cancel the fine. They added: "Wyre Borough Council is cancelling Mrs Wilcock's ticket with an apology. An internal investigation into the allegations regarding the Civil Enforcement Officer will also be carried out."