Free Traffic Legal Advice

I was making renovations to our flat in prep for the new tenant in May 2025. On 7th May I parked the vehicle in the underground parking and placed the permit on the dashboard. It is a sticker, but I only kept it until the new tenants move in so I did not attached it to the windshield. Since it was a hot day, the sticker folded, so I but a pen on top of it so that it wouldn’t roll off the dashboard.
I received a PCN that day (https://ibb.co/Y7T0R1Rw), appealed on 15th May, received no response from the operator (CPM) and between June and September I received 4 letters from the collection agency, which I duly ignored.
Now I received a letter from bwlegal (https://ibb.co/ZzkZWH6T), threatening a legal action. What, if anything, should I be doing now?
I have a screenshot of the “evidence”, taken when I appealed the case. The pictures are not clear but on a couple of them one can make out the shape of the permit sitting on the dashboard – something I had pointed out in my appeal.

Thank you, I would appreciate any assistance with it, it is stressful enough to own a flat with the cladding issue and hostile freeholder/management.

Yes, we have one parking spot/permit, we can park anywhere in the garage as the spaces are not allocated to flats.

Thank you for your response. "does your lease specifically mention the parking entitlement? If so, does it specifically mention having to engage in any 'parking scheme'? ie passes / permits / fobs etc." The lease mentions the parking entitlement (designated parking space - this assignment has morphed into general use of the underground parking without having to park in a designated space, and I have correspondence with the building management to confirm this). No parking scheme mentioned, although there is a paragraph that states that the Leaseholder has to "obey such traffic regulations as the Landlord may from time to time impose (including without limitation the designation of roads as one way streets and parking restrictions). I am not sure this is applicable to the parking schemes.
Yes, BW has our correct address.