Who told you to write that cut and paste appeal? What is all this waffle about POPLA? UKCPM are not BPA members so POPLA is irrelevant. They are IPC members. Can you even see any mention of POPLA in their correspondence? UKCPM must have had a chuckle when they saw all that irrelevant reference to POPLA and decided that you had no idea what you were on about and rejected your appeal.
Whoever gave you advice up to now should be ignored from now on. There is no danger of a CCJ. Not even if this went all the way to court and you lost. The only way you can have a CCJ on your credit record is if you failed to pay it within 30 days of judgment.
Are you even the lessee of the vehicle? If so, did you ever receive a Notice to Hirer (NtH) from UKCPM in your name as the Lessee/Hirer? What you have shown us is irrelevant as far as anything is concerned. You must show us the original NtH you received in the Hirers name. If you only received a copy of the original Notice to Keeper (NtK) from the lease company then the lease company is still the one that is liable for the charge if the NtK is PoFA compliant.
Normally, a PCN issued to a vehicle that is hired/leased, is a "golden ticket" as long as the drivers identity is not revealed. However, it only works if the lease/hire company follow the correct procedure and transfer their liability to the lessee/hirer which then forces the PPC to issue an NtH in the lessee/hirers name. They failure of PoFA comes about because 99.999% of PPCs fail to include the necessary copies of documents from the lease/hire company with the NtH.
So, please fill in the gaps and we will be able to advise accordingly. Showing your gullibility to UKCPM by thinking that a cut and paste appeal referencing the wrong AOS membership, only fuels their desire to get you to capitulate and pay into their scam.