Sorry VNA but the above post is wrong, contacting them does not identify you as the driver of the car and anyway this does not matter as the charge is unenforceable.
As far as your extract from 'this is money' that is wholly inaccurate as well, contract law cannot apply as you have to enter the car park to read 'the contract' as it posted on signs in the car park - what happens if you reject 'the contract' and drive out without parking? Most of these PPC's use ANPR cameras and you are invoiced as your number shows up even though you didn't park.
There is a lot of bad information on the web about these invoices and even Citizens Advice get it totally wrong and advise to pay then try to claim it back - no chance! MSE also has a lot of misinformation as well by uninformed posters.
This is a little hobby of mine and the best advice is found on the Consumer Advice Group forum, someone posted a link earlier in the thread.
In Scotland the registered keeper cannot be pursued by the Private Parking Company (PPC) and also in Scotland the RK is not obliged to reveal the driver. There is also no trespass law in Scotland so that's a bit different as well.
In the UK since October last year the RK can be pursued by the PPC with requests for payment, however this does not make the charge any more enforceable.
The reasons are:
1) only the land owner can claim losses for you parking on the land, the PPC's do not own the land and therefore cannot claim any losses
2) the PPC have to hold a contract with the land owner giving them rights to take action on their behalf and that cannot be used as the only reason for taking any action is trespass which you have not committed as the land owner has given you an implied right of access.
3) the PPC has to provide a breakdown of costs which show the invoice is for actual costs as only Plod, Local Authorities and Court can fine you, they can't prove the costs so the only amount they can claim is the actual losses - so for an overstay in a free car park what is their loss - exactly zero.
I ignore some and I play with others, even the most determined PPC Parking Eye get trounced every time they go near court (which isn't often) and the only cases they have 'won' turn out to be a relative, an ex employee/director or not defended.
PPC invoices are a total scam and designed to intimidate the recipient into paying when they don't owe a penny.
They send you a chain of begging letters and then pass the 'debt' on to a Debt Collecting agency which is actually just the next desk monkey along - never, ever deal with a DCA, all you need to say to them is 'any alleged debt is denied, refer to your client'
These scam artists need to be exposed and stopped and it's about time the Government got involved in this.