Pathetic service

I am baffled by the service I received from NeoStar car rentals, We rented a car from them and paid them what was required and a R2000 deposit was supposed to be refunded to us upon returning the car, we took the car back and the Managing Director was there to check/ assess the car, he told us all was fine but he had to take the car for an internal assessment and then the next thing we from them is an invoice stipulating that we damaged the car and we owe them R2650 as the Inner shied on the left is broken and there is a new dent on the Bonnet now both these thing are visible and don't need "further assessments" to be picked up. its been a week after we returned the car and to date they have not refunded our deposit back.