

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’d probably run with a small amount of white lithium grease - that should last for a good while.