Poor customer service

I bought a second hand car at Hyundai sandton end of October after collecting the car I went to them and reported that their tyres are not fine after 1 month I discovered front two tyres has old plugs and the tyres are fine looking at the car outside but inside are finished they just replaced only 1 tyre they say is a goodwill after that my car reported rear tyres then I went to tiger wheel and tyres they told me bra go and claim all tyres cause they are finished but the Dealer principal from Hyundai told me to go to head office to complain of customer ombudsman for help I'm nothing then I reported the matter to their head office he said he can't replace the tyres mind u is risky especially driving a car with tyres that are finished not knowing all they want is to push delivery after that you are on your own business and I think their head office are also scared of him cause they also said if he can't just go to customer ombudsman help me what to do with with my situation