The disabilty act doesnt give disabled people carte blanche to ignore the rules on a private car park. In this scenario its about ensuring the car park set up doesnt disadvantage disabled people. An example would be a pay on exit car park with a ten minute grace period where the payment machines were some distance from the disabled bays. Expecting a person with restricted mobility to get back to their car, get into the car and leave within the 10 minutes could easily be seen as not complying with the act.

It might also have been considered reasonable if the people in question had spoken to the staff in one of the stores explaining the situation and requesting a time extension, refusal then may well have been unreasonable. Its not the largest of retail parks, 3 hours seems pretty reasonable unless staff had been made aware of the requirement for additional time. I imagine many blue badge holders would be out of that car park in well under 3 hours. If you are going to use the disability act as a defence you will need to explain why 3 hours wasnt enough time given the specific circumstances and why Group Nexus have acted unreasonably.

Thought Id been fairly clear about pay post judgement or the CCJ will screw up your credit rating but I take your point.

The entry and exit times are still fully visible in 2 locations, on the photos as time stamps and above the photos in text.
The key missing information is the date it was sent but seeing as event was the 28th of September and you started a post here on the 8th of October Im going to go out on a limb and say the PCN is POFA compliant in which you admitting to being the driver here isnt really going to be a major issue as you will be haeld liable as keeper anyway. This will play out as follows:

You will appeal, unless you can come up with a more substantive defence than above it will be rejected.

You will appeal to POPLA with the same outcome.

You will get debt collectors letters for a few months.

You will receive a letter of claim.

If that is from DCBL Legal you will have to through the dance of providing a defence and taking part in meditation. It will probably get dropped before court.

If the LOC is from Parkineye it probably will go to court.

On the balance of probabilty with your current defence you will lose.

You then pay the increased invoice value or they issue you with a CCJ which will screw up your credit rating for 7 years.

Do you want to wade through the process for the next six months and hope its DCBL Legal or do you want it gone from your life?

None of the above is guaranteed but it is the usual process.

The keeper of the vehicle is only relevant at the time the PPC goes to the DVLA. They should also do a credit check before starting court  proceedings to check they do have an up to date address and you're not dead. Contrary to popular belief they dont want to get you a CCJ, that doesn't make them any money, it just costs money. Same with chasing someone who is deceased.

What the land owner believes isnt particularly relevant, the motorist clearly breached the terms of the parking contract, the PPC did what it was contracted to do and issue a PCN to someone who has breached the carpark rules. If the landowner had wanted to use a whitelist system to cover members they could have done, the land owner will have decided they wanted users to register everytime.

The PPC has offered the keying error discount (normally reserved for people who have attempted to comply with the car park rules which isnt the case here) which they didnt need to do. I would pay the £20, learn and move on.

The land owner will have engaged the PPC to protect parking spaces specifically for their users, is it too much to ask that genuine users follow the rules to make themselves known? The alternative is no enforcement which would probably mean parking problems for genuine users or in this case reduced revenue for the centre which would also impact centre users.

Im not sure exactly where you parked but I would say the land reg image also shows the pavement outside of their clients boundary. Sounds like their cameras are misaligned. Reallyneed to see the PCN  and images they have to identify where your plate was when it was captured. Even then if you only crossed into their.and at the start and end of your parking you wouldnt have exceeded the consideration period. However if they have two images showing you did cross their land boundary it maybe difficult to prove the car didnt remain on their land whilst parked.

Need to see the PCN.

Was your vehicle parked in  Lidl for 1hr 42 mins?

Its also likely you will lose a POPLA  appeal with the didn't actually park defence.