It all depends on whether you are willing to fight it and risk not being successful. The main point of appeal will be the fact that the Notice to Keeper (NtK) is not fully compliant with all the requirements of PoFA 2012, paragraph 9(2)(a) because it does not state a "period of parking". There is persuasive appellate case law where the court confirmed that without a "period of parking" specified, the notice does not comply with PoFA and therefore there can be no Keeper liability.
Only the driver can be liable and the operator has no idea who that is unless the Keeper blabs it, inadvertently or otherwise. So, if you are fighting it as the Keeper, you only refer to the unknown driver in the third person. No "I did this or that", only "the driver did this or that".
As you are dealing with an IPC member, this will be a protracted process and will end up as a claim but will either be struck out or discontinued before it ever gets to a hearing. You are looking at anything from nine months to over a year before it is concluded.
If you do want to fight it, then read the following for your initial appeal and come back when that is rejected:
There is no legal obligation on the
known keeper (the recipient of the Notice to Keeper (NtK)) to reveal the identity of the
unknown driver and no inference or assumptions can be made.
The NtK is not compliant with all the requirements of PoFA which means that if the
unknown driver is not identified, they cannot transfer liability for the charge from the
unknown driver to the
known keeper.
Use the following as your appeal. No need to embellish or remove anything from it:
I am the keeper of the vehicle and I dispute your 'parking charge'. I deny any liability or contractual agreement and I will be making a complaint about your predatory conduct to your client landowner.
As your Notice to Keeper (NtK) does not fully comply with ALL the requirements of PoFA 2012, you are unable to hold the keeper of the vehicle liable for the charge. Partial or even substantial compliance is not sufficient. There will be no admission as to who was driving and no inference or assumptions can be drawn. PCM has relied on contract law allegations of breach against the driver only.
The registered keeper cannot be presumed or inferred to have been the driver, nor pursued under some twisted interpretation of the law of agency. Your NtK can only hold the driver liable. PCM have no hope should you try and litigate, so you are urged to save us both a complete waste of time and cancel the PCN.