I want to take the car back to Lexus to fix properly and my refund back

I bought a car from Lexus in August 2020 and September I had a very serous problem and the Tylor suggested that I take the car to Mercedes Benz and they charged me and he promised to pay for that expense and he did not pay. I then spoke to their principal dealer Chris Jones who said they need to fix the car from the 23 - 26 November and they did not fixed instead there was more problems than before. I then wrote to Chris Jones on the 9 December 2020 he did not respond with all the proof but he did not respond until to date.