Never use this business!!!

I have just experienced one of the most shocking things in my life! I rented a car from Hertz car rentals. Paid a R15 000 deposit. When i returned the car a post inspection was done upon arrival. The lady said all was well and signed off the vehicle. I later received a notification from the company that there is a dent on the one door (which they provided a photo of, how do i know this is the car i drove?) and they are now with holding my R15 000 deposit until i explain what happened. I can assure you that dent was not there when i dropped it off and was also not noticed by the post inspector. Then they took R3376 off my credit card for the damage without my approval and have still not returned my deposit. Is this a ****?? I am beyond shocked.