Car accident claim

I was involved in an car accident two weeks ago. The other party who was renter from Hertz hit my car. I called the Hertz claim department for claims many times. However, I still have no responded at all. They told me the person who drove the hertz car wasn't Hertz renter. But I have all police report and information and stated that the car was from Hertz. Now, Hertz turn around and said he wasn't renter from Hertz. What am I goin to do? I have been waiting for two weeks. I even filed a claim from my own insurance company to try to push Hertz do something about it. I need some advice. Thanks

Your insurer should investigate for you.

State laws will determine if Hertz is responsible for the "non permissive user". If the person was not on the rental contract, there may not be coverage thorough Hertz.
In some states only those listed on the rental contract are covered. Your carrier needs to handle this claim on your behalf and attempt to subrogate the appropriate party.
This is why you should always carry UM coverage on your personal auto.