Plan A is to get PALS to have the Parking Charge Notice (PCN) cancelled. Have you tried that yet?
CPP are owned by ParkingEye and their Notice to Keeper (NtK) is identical to those issued by ParkingEye and therefore contain a PoFA flaw, meaning that they cannot hold the Keeper liable, only the driver, who they ave no idea who that is unless the Keeper blabs it to them, inadvertently or otherwise.