Dealer refusing to fix car issues.

Hello. I bought a pre-owned mercedes benz c class at Motus Toyota Bryanston around 27 March 2024. I was promised that everything that is wrong with the car will be fixed including scratches on the car etc. After taking possession of the vehicle I realized that thre is a crack on the medal part on the Rear bumper which the dealer promised to fix but didn't. The car is not driving much but yesterday when I was washing the car,the fuel car just completely came off which is amazing because the fuel cover is completely electronic and can't just open on its own. However it just came off completely , and I noticed when I lock the car,the car wasn't beeping as usual even though it locked. I informed my sales person Rajen Subramoney but he refused to assist me saying his manager Ricardo David says there's no report on their side that shows the car had issues with fuel cover. So when I in the process on purchasing this car ,I was promised severally that if anything were to go wrong within 6 months of collection I can bring the car back for them to repair for free. They promise lies and lip service and they don't honor their word. So stay away from this dealer if you don't want a headache.