broken aircon

My hired vehicle from Avis which I got and drove from Queenstown to East London had a malfunctioning air conditioner. I advised Kim at the East London branch and she said she was sorry. I do not see why I should pay the amount I have paid for this rental when the vehicle was not in the form it should have been in. Vehicle details are: Group B, Polo Vivo, CA 224627 rented on 25 August 2015.<br> <br> The vehicle was an upgrade from a group A because it had to be transported to East London for a service. I was not notified of the malfunctioning up air conditioner as I would not have agreed to the upgrade.<br>