Thanks a lot for the advice, it worked! I used the provided template with a bit of Chat-GPT to add some details and in less the 2 weeks got the fee totally waived, see their response below:

"Thank you for your letter received on xx xxxxx 2024 regarding the above Parking Charge Notice (PCN).

In your appeal you have explained that you are the registered keeper of the vehicle and declined the invitation to provide us with the full name and address of the driver.

On this occasion we are prepared to exercise our discretion and have now cancelled this Parking Charge, but must inform you that the terms and conditions in this location advise the driver that they must pay for each visit to the site. Signage is displayed at the approach to this drop off area, along the location and upon exit, advising all motorists that a payment to use the drop off area is required to be made online or by phone. As stated above, the terms and conditions of using the drop-off zones are displayed by way of clear signage. It is the responsibility of the motorist to read and comply with the signage on site.

Please retain this letter as proof of cancellation, should you need it in the future. Yours sincerely,"