Unfortunately you need legal help.  If you are injured, consult and hire a personal injury attorney who can help get the insurance company to realize that they are putting their insured at risk.
If you are not injured and the damage to your vehicle is less than $5,000, you can sue the person who hit you in Small Claims Court.   You will need to show that you did not cause the collision and that the other person is responsible.  You will also need to show how much it will cost to fix your vehicle.  If you also need to show how long it will take to repair your car and how much a rental will cost.  The insurance company may respond once their insured is served.  If not, they may try to send an attorney to same claims which if that occurs, you need to remind the judge that lawyers are not allowed in Small Claims.