Final Demand - Oak Legal services for UKPC. Parked in an area where no parking is allowed - Nine Elms

As title, parked in area where parking is not allowed at Nine Elms, Battersea. No response was made to UKPC now received final demand letter from Oak Legal Services.  Please advise on next steps.

See attached letters received.

I believe that this could have been challenged earlier but we are where we are. Please post up the rear of the PCN I cannot see see any reference to the creditor thus far. Similarly it would be beneficial to see any signs that are present. There has been no initial appeal so I can only see this heading towards court action unless the defence is solid or they decide not to continue.Ignore the debt collectors letters and you will probably get LBC and further possible court papers.

Please see rear of the pcn. Unfortunately unable to get pictures of signage as I have not visited the area since. I should add context that the driver was carrying out a private hire booking which evidence can be provided. Which shows he was waiting and not parked.