INCORRECT  CAR REGISTRATION :  USEFUL CASE LAW TO KNOW

Thorton v. Shoe Lane Parking ( 1971 )   Court Of Appeal

Held : The ticket machine constituted the offer. The acceptance was by putting the money into the machine.

Butler Machine Tools v. Ex-Cell-O Corporation ( 1979 )
Court Of Appeal

Held : The offer to sell the machine on terms provided by Butler was destroyed by the counter-offer made by Ex-Cell-O . Therefore the price-variation clause was not part of the contract. Indeed,the contract was concluded on Ex-Cell-O's terms since Butler signed the acknowledgement slip accepting these terms.
So when there is a battle ( of the forms ) whereby each party submits their own terms THE LAST SHOT rule applies, which means a contract is concluded on the terms submitted by the party WHO IS LAST to communicate those terms before performance of the contract commences.

In cases where motorists have entered incorrect details, the following defence could go along these lines.   
The ticket machine constituted an offer. This offer contained a term stipulating that the full licence plate details need to be keyed into the machine. By varying this term and only keying partial or incorrect details ,  a counter offer has taken place.
Since the machine was not programmed to reject any counter offer, acceptance went ahead  the moment the machine took and accepted the money.
Therefore the ticket was valid.
This analysis of the parking contract is the equivalent of the battle of the forms. 

But what if this defence doesn't work ?

Well , proceed along these lines. If the ticket is indeed declared invalid ( for the car driven into the car park ) , then having an invalid ticket is the same as having NO TICKET AT ALL. Therefore by not having a ticket , it would seem logical to assume that no payment has been made for parking the car recorded by the AVPC system. 
This means the PCN is based on an erroneous claim. The violation should have stated " non-payment " as opposed to " displaying an invalid ticket ". This makes the civil wrong one of trespass , in which case damages can be nothing more than nominal.
However, the reality is there has been no loss of income , because a tariff had been paid for a car which didn't enter the car park and use up a parking bay. The company therefore was never out of pocket as a consequence of this administrative mistake.