OK say where the parking took place exact address/postcode and we will ahve a look on gogglespy to see what we can see from the public highway.
Now as you mention permit scheme then it is likely that the notices there are not a genuine offer of terms for parking butinstead prohibitive such as "permit holders only". it wont matter what other rubbish they spout after those words as it becomes a matter of trespassas you didnt have a permit so nothing else applies.
If the sign says free parking for permit holders, everyone else pays £100 to a bunch of greedy cowboys then that would be legally binding.
I waited and I waited and have ignored the repeated requests for money inclusive of them sending me a goodwill gesture to reduce the 'fine' back to the original if I paid up within 14 days of the letter being sent.
Whilst all this was going on I complained to the landowners, whilst preparing myself for my day in court and they too felt the charge was ridiculous so they requested it be cancelled and it apparently has been. Thanks for all help offered.
Don't touch them owe me £500 since January 2019 make excuse after excuse. Seem they always have software problems sending money out. Keep saying they will call back or email nothing been chasing it now for 6 mths the phone staff always have the same banter we will chase it up and get back to you then nothing!