Thanks, I had no idea how to find that out, so that's really useful. I think the approach my friend will take is to send a firm but fair appeal that doesn't identify the driver but does clue them in that we know our stuff, and if they continue to pursue this then approach Savills with a polite but firm 'you're going to be jointly and severally liable for my legal costs if you don't back down now I've proved the fee was paid and you have no actionable loss'.
Here's what I'll get the keeper to send, unless anyone has a good reason to change it:
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I am appealing Parking Charge Notice number xxxxxxx, issued for "Whole Period Of Parking Not Paid for”, because the driver paid the parking charge in full, and retained the ticket that irrefutably proves this.
I attach a scan of the ticket, which proves that you accepted a payment of £1.50 and issued a ticket that allowed parking until 11:33 on the day in question. As your own evidence shows the driver left the car park well before this at 10:56, it is clear that no further payment is due.
I note that despite the driver entering the full VRM into your machine, the ticket you issued only shows it's first four characters, which may be why you have not correctly allocated the payment you accepted.
I look forward to receiving confirmation that you have cancelled this Parking Charge Notice.
You have requested that I supply the following information:
My Name is xxxxxxxxxx
My Address is xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
The Vehicle Registration Number is EX18xxx
The Parking Charge Reference is 7720289
I confirm that am the registered keeper of the vehicle, however I am under no legal obligation to identify the driver and will not be doing so.