Canceling purchase of a faulty vehicle with We Buy Cars - The ****TEST service I have ever received

I have bought a 2021 Haval H2 from We Buy Cars Midstream in September 2022 with roughly 28 000km on it. A few weeks after I have bought the vehicle the engine light came on while on the highway. The car was almost due for it's 30 000km service so when I booked the service I also asked them to check why the engine light was on. Turns out that the CAT of the vehicle was blocked. This made no sense to me as the car haven't even driven 30 000km yet. The warranty of the vehicle do not cover for the replacement (Or cleaning) of a blocked CAT and quoted me R16 700.00 for the replacement of the part. The vehicle has been in my possession for 2 months and already I have to start paying for the replacement of parts. Why did I buy a vehicle with a warranty then? Also, the Dekra report of the vehicle did not mention anything about a faulty or possibly blocked CAT with the initial purchase. I also did not agree to receive the vehicle with the faulty part as everything was in excellent working condition according to me. I returned the vehicle (And everything with it) to We Buy Cars Midstream on the afternoon of 23 November 2022 to cancel the initial purchase. Wynand Pieterse (Customer care manager) assisted me with the process and ensured me that they will finalize everything within two to three days and he will provide me with regular updates. This was a gamble which I took because the Haval was the only vehicle we had between my wife and I. Luckily I work from home permanently, but my wife needs to go to work every day. Since then I have probably called Wynand 60-70 times where he only answered 1 of those phone calls. All of the documents expire today (29 November 2022) and the installment for the vehicle is also going off from my account on 30 November 2022. Now I have to pay for a vehicle that is not even in my possession anymore. In the meantime my wife and I need to ask other people to drive us around as the service from We Buy Cars are non existent. THIS IS THE WORST SERVICE THAT I HAVE EVER RECEIVED IN MY ENTIRE LIFE. There is no feedback, no commitment and no urgency taken for customer queries which leads me to believe that I am not being taken seriously. We Buy Cars will NEVER have me as a client again. They are quick to act when you want to buy a vehicle, but their after sale service is absolutely ****!!!!!