Rocks damaging my car

These rocks have been placed on the grass verge for over a year and the rock on the left has been placed significantly closer to my side of the property.

We have cars with low bumpers and every time, we try to reverse and come out of the driveway, the splitter and bumper gets trapped and damages our car , and impeded our safety.

Everytime, we try to move it towards the centre to make it symmetrical to the rock on the far right hand side, someone puts it back to our side to deliberately cause harm to our cars.

We paid over a grand to the council to get a dropped kerb , not to experience this every day stress in the morning.

Moreover, this is a private road, no other houses have rocks placed outside. I would like an explanation of why is this kind of act is allowed? Will the council pay for our damages?