Your VRM is available 24/7 when your car is on the highway, therefore there's no purpose in withholding it here.
As for the PCN number, this doesn't identify you.
We need both to check their website.
As regards parking legislation, the issue boils down to whether you were parked within the scope of waiting and no loading prohibitions. We need photos. If the website cannot assist, then you'll have to arrange to take some yourself I'm afraid.
As regards: I wasn't aware of the loading restriction but looking on my dashcam footage there seems to be some tiny 'No Loading' Signs that as a disabled driver it would be dangerous for me to avert my eyes to see.
As you know, a driver's obligation is to observe markings and signs, in this case you can park, look and, if restricted, move off without being in contravention: it's not done in real time from the driver's seat.