You should always appeal to the parking operator first and follow their internal appeals procedure. Details on how to do this should always be found on the back of the parking ticket. This is mandated by the Code of Practice of the Accredited Trade Association (ATA) that the parking operator belongs to.
Appealing a parking ticket will fall under two categories:
1/ Is the parking ticket lawful?
2/ Does the motorist have mitigating circumstances which caused them to incur a parking ticket?
The Lawfulness of the Parking Ticket Issued on Private Land?
Appealing a parking charge on the basis on whether it is lawful comes down to three basic issues:
1/ Does the parking charge have a legitimate legal basis in contract law?
2/ Has the parking operator satisfied the evidential burden to prove that the motorist breached the terms and conditions of the parking contract?
3/ Has the parking operator breached the Code of Practice of the respective Accredited Trade Association (ATA) that the operator is a member of?
If any one of these conditions is met, the parking charge will almost certainly be rendered void.
Mitigation
Mitigation, or mitigating circumstances, are any event or circumstance that might lead a motorist to incur a parking ticket, but do not extinguish the motorist’s legal liability.
Any number of situations may amount to mitigation. Common examples may include medical emergencies where a motorist may have had to overstay or park illegally in a non-designated parking area.