Bad service.

My insurance booked a car for me from them. When returned it on date was supposed to be returned. When we returned it was fully of petrol and clean. They check everything and they said everything it's fine. On our way back home, I got a call from them they said there's a mark on the boot, seemingly like someone was trying to break the car. Me and my husband we never saw that. On the following day send me a form to sign, I took off the wording saying I knew about the damaged, really I was not aware about it and they never mention it when we brought the car. On the next day I received a sms saying the damaged cost will be R3600. Remember they hold R1500 out of my car and they never return it. Today they deducted FNB:-) R2654.00 reserved for purchase @ Avis Rent A Car from Private card. Which is I'm not aware of it. Please refund my money. I will report it as a *****