Avis rents out faulty cars and customer to pay for "inconveniencing" Avis

I hired a Polo TSi on 29 June to 4 July 2018. I collected the car from downtown Cape Town and agreed to return it to the same place on 4 July. I left the luggage rack at home and went to Oudtshoorn. While in Oudtshoorn I realised the car was faulty, it would not lock. Avis brought me a replacement car, a Ford Focus, in Oudtshoorn. The car came from the George office. I reported that the luggage rack issue to the rental agent who brought the car, Peter. To my disappointment the replacement car turned out to be faulty too, the one wheel kept losing air. I decided to leave with this fault, which meant a number of stops at fuel stations. In addition to the inconvenience, I probably paid more in fuel as a result of this. I returned the Ford Focus to Cape Town on 4 July, plus the luggage rack of the TSi. To my disbelief, Peter from George tells me to collect the luggage rack from downtown Cape Town and courier it to him in George, that downtown Cape Town does not want to incur the extra cost of courier. So I must not only incur the extra fuel cost, stop at every garage to refill the faulty wheel and be limited as to where I could go due to a car that would not lock...but in addition Avis wants me to courier the rack, to George where they have the TSi. Unbelievable