I've been given a Euro Car Parking fine and what really aggrivated me was that I have a permitt to park there and they still gave me the ticket - when it was displayed!
It was the Easter Weekend of this year, and it turned out because it was a bank holiday and it was going to get busy, they had decided that employee's who work on the saturday can't park their cars in the usual place (I don't work for the sainsburys, but am involved with IT systems for a company inside the building).
When I returned to the car the ticket was there, and it had been fine before - the reason on the ticket 'parked more than 2hrs'. I was pretty angry - ripped the thing off the windscreen and walked into the store. Went to the reception where some damn incompetent woman (who was about 21) stood there. Explained the situation calmly, when she replied, 'Well you have no right to park up there today - its closed today due to Easter Weekend'. If I had of been told ofcourse, I would have moved it, but where I parked my car, there were 7 other cars with tickets who were staff!!!
Told her that was not the case as there was not inidcation of clear sign and her responce was 'Pay the fine and park somewhere else.' Erm, no - get me your manager. Manager came down, talked to her, she realised they didnt have a sign and backed down, fine was cancelled. Since then I've got an unlimited permitt which actually means I can park anytime for as long as needed but they don't have a leg to stand on for most of the fines they dish out.
They can take you through courts though - if you're just a customer your probably going to need to pay up.