You cant just go up to them and say you want compensation.
1) When you receive a parking ticket, contest it. Write your own letter contesting the ticket as well as ticking the boxes on the actual ticket. At the end of your letter state that you will be charging them £50 for this letter if ticket is not cancelled.
2) They will send you a letter back rejecting cancellation of ticket and rejecting your administration costs (note that they cannot "reject" your administration cost)
3) Write another letter stating you want your case seen by adjudicator, (make sure you give them all the facts of the case and highlite the legalities and laws you want to put into action)
NOTE--
This is not being crafty or bending the law. The FACTS will get you off. There is no way that a parking attendant can legally give you a ticket as they will be breaking at least 3 rules under the Road Traffic Act each time they issue you with a ticket.
4) Keep a count of all the letter you write to them. After the adjudicator has seen your case 2 things can happen;
4a) he will reject your case - in which case you can appeal his/her decision and take the matter to court. Write to them and ask that your case be seen by the court and ask for a date. Also do not forget to add administration cost.
HOWEVER, once the court has sent you a date and sent a copy of the letter to the traffic enforcement agency, ie, Transport for London, the enforcement agency WILL contact you and cancel the ticket.
4b) He will accept your appeal and cancel your case.
5) Send a letter to them saying that they owe you money (they cannot say that they cancelled the ticket as that is a seperate case and they have settled - the letter they sent you saying ticket is cancelled)
6) If they reject your claim, go to
www.moneyclaim.gov.uk and make a claim against them.
7) They will "contest" your claim, however once a court date has been sent to them, they will give up and settle your claim.
HOWEVER - They do take the p*ss, because when they actually give you compensation or any payment it comes from their "Petty Cash", as thats what it says on the cheque. So you can imagine the kind of cash they deal with if 500 quid is petty to them.
Hope this helps, let me know if anyone needs any help.