Para 3.4 of the Code of Practice requires them to have prominent signage at the entrance notifying the changes to terms. If you can get some pictures of the lack of signage, then you've got good grounds of appeal. The invitation for the keeper to pay or nominate the driver is also missing. Make sure you don't identify the driver inadvertently during the appeal. UKPA will probably reject, but you might have more luck at POPLA.