Unprofessional Behaviour

I had rented a car over a week ago through my insurance. When my insurance suddenly stopped the rental, I was told to immediately return the car. I organised to carry on the rental myself as I still don't have a car. I went to Bruma Avis last Friday to redo paperwork and left with the same car. I called this week Wednesday to extend the rental until the 25th as my car is still not ready. Yesterday I get a call from Avis asking if I can bring the car back to change, as they have sold the car I am using. I said no as im at work all day. She then asked if I can bring it the next day! ABSOLUTELY NOT! I have booked this car til the 25th and its very unprofessional to sell the car im using and expect me to just stop my life to return it to you because you were stupid enough to sell a car that's being used! Who does this?? I will never use Avis again. How dare you treat paying clients like they just sit around and wait to do your bizarre biddings.