Whenever you rent a car, make sure you take photographs at the time of rental and when returning and get a receipt clearly stating that no damage was found on the car. But in this case that is moot. I would ask for clear photographs of the damage, the police report with details of the accident and the witness statement and the details of the police interview. All this would be provided to you anyway if you went to court. Find out if your credit card provides insurance and turn this over to them to deal with. They have a lot more clout than you do.