Yo, def get the police involved or atleast conatact them to see if they can help you at all(prob not, cuz what are they good for?) i would also take them to court, they now have no insurance on their car,the girl was driving underage, and they are refusing to pay the fines.

OH, and btw DO NOT, i repeat DO NOT, go to the shop they tell you to go to. You are allowed to pick ANY shop you want for the repairs, no matter how expensive they are. I would suggest either taking them to small claims court, or hiring a lawyer. GOOD LUCK! and dont puss out! Stick it to them like they are sticking it to you!