Lying about a car scratch in order to keep your deposit!

I rented a car and paid a deposit. Then I returned the vehicle without a scratch, I literly drove like a grandma and took really good care of the car. 2days after they phone me and said there was a scratch and they are keeping my deposit. They could not send a picture because they already fixed it. I knew they were lying. There was no scratch Avis. *******. They send me a cartoon picture of a car with a small cross mark.