There's a phone app called 'SnapSendSolve', you take a photo of someone doing something like this, blocking a driveway etc, and send it off. They send it to the appropriate people, cops, council, whoever. Your identity never comes into it.

If they had a disability permit it'd be fine, the yellow lines are there for extra space. The permit should have been displayed somewhere visible though (typically the windscreen but I don't know if that's a requirement).

If it were a council carpark you could report non-permitted use to the local council, being Bunnings it's probably private land though so you'd have to find out whose responsible for their parking enforcement.

I don't know if you're still on the spot, but I would get a picture that clearly shows the sign and let someone from Bunnings know. They should be able to contact whoever is in charge of the parking lot about it. And if not... Well.

Honestly, I’ve been looking for stickers to put on the windshields of these cars with dodgy or illegal parking.

The problem is, its simply too convenient for these people to keep acting like assholes. If everyone was plastering their windshield with difficult to remove stickers, the 30s they save, would no longer be beneficial.

And, whereas people in larger cars should be driving with more care, they are instead doing the opposite (I regularly see them rock up to shopping centres, and just park partially blocking a second spot, because they can't be fucked fixing their parking).