It is an appeal point. Because of the failure to use the correct wording in the NtK according to the Protection of Freedoms Act 2012 (PoFA), they cannot rely on that act to hold anyone but the driver liable for the charge.
They have no idea who the driver is. All they know is that you are the keeper. Because they cannot rely on PoFA, they cannot transfer liability from the driver to you, the keeper. The keeper and the driver are two separate legal entities and no assumptions or inference can be made.
So, as long as the keeper has not identified as the driver, inadvertently or otherwise, the keeper cannot be liable for the charge. They can only hold the driver liable and so they must go find the driver and chase him/her. You could wish them luck in doing so.
However, you are dealing with an ex-clamper and the IPCs kangaroo court of secondary appeals, the IAS. Neither are likely to uphold that appeal point because they are money grabbing shysters. It would probably have to end up as a claim in the county court and the only truly independent arbiter would be a judge who decides whether you, as the keeper, owe the shysters a debt or not.
