Sold me a Toyota Hilux with many faults and refused to exchange it

I traded in a VW Polo TSI 2015 and bought a Toyota Hilux SRX 2.5 d4-d 4x4 2014 for business on August 23th, 2017. Two weeks later it started to give me problems. I reported it and I was promised it will be attended to. It took them 6 weeks to fix the 4x4 fault that they knew about early this year, as per the report from Toyota Mafikeng they knew that the gear box needed attention yet they chose to sell me the car in that bad state. The gear box was attended to but it doesn't drive smoothly, which means I will refrain from using the 4x4 gears I guess. What pains my heart even more is that, earlier this year, some white guy came with the intension to buy the same car and he refused to take accept it, yet when I returned it they refused to exchange it...maybe it's due to the colour of my skin. I reported the matter to MIOSA, they say they have many cases, so I guess I will retain this pick up truck with many problems. I don't think I will ever go to Autopedigree Mafikeng to purchase a vehicle ever in my life. The branch manager and the regional manager do not have the best interest of customers at heart.