i got plaster on my car(witch is parked in my payed parking space) from the neighbours building witch is in renovation

I already called them in April, as they started renovating, to tell them that they had no safety and dust nets, and my car was full of rocks and dust. They installed a net, but you will see in the pictures how they installed it. I called them today and sent pictures. At first, they said they would pay just for a cleaning. The car clearly needs detailing, maybe polishing. The car is almost new; I bought it in December. I told them I would call the police, and then they said they would pay for the damage. what if i repair the damage and they dont pay?