In your initial appeal, did you blab the drivers identity? Only you know the drivers identity. Until you blab it to them, they have no idea who the driver is and unless their Parking Charge Notice (PCN) is fully compliant with ALL the requirements of POFA 2012, they can only pursue the
unknown (to them) driver.
Obviously, if your appeal was anything like your opening post, it is clear to anyone that you were the driver. If the PCN was issued as a postal Notice to Keeper (NtK), that means that the drivers identity is obviously the same as the
known (to them) Keeper.
For reference, the driver should only ever be referred to by the Keeper in the third person. No "I did this or that", only "the driver did this or that".
Have a read of this and then show us the PCN and what you put in your initial appeal, verbatim.
READ THIS FIRST - Private Parking Charges Forum guide