Tempest car hire

We hired a car from JHB over the Easter weekend. The car was inspected on collection. It was in pristine condition. Drove the car to Durban, drove it back at the end of the Easter weekend and returned it. Upon return Tempest accused us of 1) having an 'accident' which damaged the door panel of the car, 2) taking the car to a panel beater to fix the damage and re-paint the door panel to hide the fact that it was in an 'accident'. They now want us to pay an additional amount for the so-called excess and refuse to release our deposit amount. We were not in any accident while the car was in our possession and the car was not damaged. We had the car for exactly 4 days, two public holidays and 2 weekends, and for two of those days we were on the N3 travelling to Durban. We did not have time to even do what they alleged we did. Their accusation is ludicrous and we are still waiting for our deposit. They are blatantly lying, covering up their own mismanagement by trying pin a previous accident/ damage on us. NEVER AGAIN!