Car without working AC sold to me, now they're ignoring me.

I bought a car from Imperial Select Menlyn in November 2020, two days after receiving the car I realised that the Air conditioning doesn't work. I immediately contacted the salesman handeling the sale. He had kept me on a leash ever since. First I had the car regassed, they were supposed to refund me, still waiting. That didn't work though so I took the car to the manufacturer and theres an entire part (evaporator) that doesn't work and which costs almost R20000. I emailed the invoice to the dealership, contacted the same salesman several times, sent an email, no response. Now I would like to know how could they sell a car that does not have AC in working condition and why are they quiet and not assisting me now.