Car rentals they add money just not to pay back your deposit

I rented a car with eastpoint and the car was taken in, I called and they said they will get back to me. Now when I called them they told me my account is closed and I was not told. The amount now has gone up, they telling me I owe them R19 000 which I don't even know how did we get there. Asked for explanation they telling me the person who closed it is no longer working there.