The way we would normally advise the Keeper of a vehicle that has received an NtD to appeal only as the Keeper on day 27 after the NtD is issued. This is because sometimes the operator will then respond to the appeal, invariably rejecting the appeal, but having failed to issue an NtK, cannot then rely on PoFA to hold the Keeper liable.
IN this case, the NtD itself is not PoFA compliant as it does not define the period of parking. This invalidates the PCN and they cannot transfer liability to the Keeper if the driver is not identified.
Whilst PCM have ignored the fact that their PCN is not PoFA compliant, they have threatened Keeper liability in the NtK. As they are IPC members, I do not advise trying to appeal to the IAS as that invariably is a waste of time. Others will disagree and if you do try, remember that you have a less than 5% chance of succeeding.
The ideal way this will be sorted is if they try to make a claim in the county court for the alleged debt. Here you will have around a 99% chance of winning.
You only need to safely ignore any debt collector or Debt Recovery Agent (DRA) letters. We don't need to see or know about them and you can safely use them as kindling. The DRAs are not a party to any contract allegedly breached by the driver and the are powerless to actually do anything except try and scare the low-hanging fruit on the gullible tree into paying up out of ignorance and fear.
If/when the Keeper receives a Letter of Claim (LoC) then came back and show us for further advice.