Hi,
If they are parked, preventing safe access to your property then it sounds like they may be in contravention of the Road Traffic Code 2000, Reg 166. But that's not something you could use to sue them with, however you could report them, Take photo's.
However if they have forced you to drive an unsafe route for access and egress of your property causing damage to your vehicle you may well also have grounds to pursue them for civil damages. You could get a quote for the damage and take them to small claims court to recover the costs. I hope that helps.