Honour upgrade default cellphone by Mtn

On the 15th og August2019 I upgrade my Mtn contract at MTN KEYWEST KRUGERSDORP. After 2 months on 16Oct2019 mycell phone said overheat and shut down automatically. Iwent back to MTN KEYWEST KRUGERSDORP ON 25th October2019 and explained to them what happened as this was still under warranty. Up till then I received good customerservice. Then it started. I was told to wait2 weeks. Nothing happened no call nothing. I called them numerous times and was told by them its a software problem with the Samsung A20 and have to wait another two weeks and phone was full of scratches and dents, which is a lie, as the consultant at time of taking the phone CHECKED EVERYTHING, EARPHONES AND CHARGHER AND BOX. All I want is my phone in good condition and workable back. Is that to much to ask, or should igo.to the consumer council. Will MTN KEYWEST KRUGERSDORP HONOUR THEIR PROMISE TO SORT OUT PROBLEM PLEASE. MR J H MULLER *** contactnr during day *** Mrs J E Muller. Thank you.