Bad service attitude and no response

I am a tour operator. I rented a car from first. on the morning taking out had a bad attitude. (a female colleague who was with me can ellaborate). Furthermore on the evening before returning the vehicle i parked the car and waited for my colleague and then heard a thud. The morning of returning the vehicle we were sitting on the grass and saw damage below the passenger door. I had taken out full insurance. and yet was billed for the damage. On writing back initially I received a response which indicated that the charge was because in their terms and conditions the vehicle is not covered if it did not come into contact with another vehicle or object. I responded on 08-09-17 "Please explain how damage could have occurred if vehicle did not contact with another object" I am still waiting for a response. I forwarded to the national sales manager on 05-12-17. I am still awaiting a response and refund.