De*****ed and left with a broken car

My husband and I recently purchased a vehicle, "Dekra" approved under their so-called "Category A" - which is only available on finance by the banks. 4 Months later, the car started having issues, we had a diagnostic done, only to find out that the previous owner had overridden the thermostat error. Obviously, we weren't aware of this as it was'nt showing when we purchased it. We lodged a claim using their recommended insurance, "Innovation", who declined to fix the car because they found that this part was an existing fault someone had tampered with. WeBuy Cars sold us this car under Category A, and Dekra approved it, which should have been Category B. We honestly feel like we have been de*****ed by WeBuy Cars, selling ***** cars under specific A standard categories. We have already spent R30 000 to fix a problem, and we have now been given another bill of R35 000 to fix the thermostat problem that existed when WeBuy Cars sold us this Car. We are still paying our monthly instalment for a Car that is not working! and have another bill of R35 000!!! and have already spent R20 000. With that kind of money we could of gone to a reliable delership. We spoke to Meghan she advised that we are out of warranty, our warranty ended the 8th February and we sent a complaint 15th February???? Shy of a few days, how technical can you be? We are still in the 6-month warranty period, and we are in the 6th Month still. This ****************, If I knew what I know now, I would have gone to a reliable dealership!