terrible after sales service

We bought a Chevrolet Utility bakkie/pickup from Tommy Martin Princess Crossing. When we collected the vehicle, the bin was not rubberised as agreed and the rear window was not fitted. I made arrangements for the bin to be rubberised and the rear window to be fitted. The sales lady told me that it will be done the same day as the company who fitted the canopy will rubberise the bin and fit the window. When I got my vehicle back for a second time the bin was rubberised but the window was still not fitted. A few days later I went to speak to the sales lady who had a very bad attitude and told me that she does not have to speak to me as the finance was not taken out on my name but on my father's name. I am the one who is paying the installments for that vehicle as my father took the finance for me. So after a while of arguing the sales lady them explained to me that the rear window was not charged on the quote and that she removed it from the quote because she had a previous client who's rear window started leaking. I was then told that if I want the window I have to pay for it then it can be fitted. I recorded her saying that she removed the rear window off the quote. I want a rear sliding window fitted on my vehicle.