Bidvest car rental Kathu ripping me off

So disappointed with Bidvest car rental in Kathu. I rented a car there they gave me while it's dirty we did inspection together some small tents were not registered on the list they said it's nothing. Now whn I returned the car I washed it so they saw those small tents they claim that they don't know them now I have to pay and they can't give me my deposit back