SO CALL ANOTHER NUMBER! For crist sake. Call the police, call the local wardens. Go get their friggin plate number. If you knew where they were parked. A plate and a phone message would have got the ball rolling. Have you called about it since????
Phone lines are busy and so are people you could have made an attempt at getting a plate. What your recommending on here will only lead to trouble for people. destroying personal property wont solve to problem. If you have that much info that your sure they are the people commiting the offense why would you do that vs turn them in. Good way for someone to get hurt.
....its like taking x-lax when you have a bad cough. It wont clear up your lungs, but it sure stops you from coughing