Rental Car Contract "fees"

I rented a car and was rear-ended by someone without insurance. I did not pay for the "additional insurance coverage" from rental car company when I rented the car. Therefore, my insurance company had to pay for most of the damage However, I still owe the deductible to the rental car company. Additionally, the rental car company is charging me for "Loss of Use" and "Administrative Fees" that were written into the small print of the contract. They first charged me $452 for these fees. However, when I argue or ask for clarification and especially when I say I am going to talk to a lawyer, they agree to "reduce" these fees down to $152. I think I am getting unfairly charged – but I don't know what my rights are.

First I would speak with someone higher up demanding that those fees be dismissed. If you get nowhere, then tell them they should be dealing with your insurance company regarding this issue.