MTN's pathetic Customer Service and no appreciation of it's Customers

I have been having a problem with my phone purchased from the MTN store at the Galleria Shopping mall in Amanzimtoti, Durban since March last year 2020. I have been continuously sending the phone back to the store for repairs due to technical faults on the device which to me is absolutely pathetic and inferior quality, both in workmanship and in their (MTN's) customer service. To add salts to the unnecessary wounds caused by MTN through this, I had to suffer the loss of income from my work which requires me to use my phone as it is the key tool needed to perform my job and this too being a total of 20 weeks resulting between the phone going to and fro the store and the repair center each time a fault was picked up. When I viewed my dissatisfaction to the store, I had a rude and disgruntle sales consultant speak to me as if I'm an idiot and of no value to the chain line. I had taken my concerns and issue with the MTN customer complaint and expressed that I need to be replaced with a conforming device or re-reimbur*****t of my money paid for the device and that i needed to be compensated for the loss incurred which has and still is having a ripple effect on everything else due to MTN and their disastrous customer service and quality control and assurance failures. The customer complaints consultant did try initially to help but I have been very patient and kind despite the fact that the problem once taken to him has been taking about 3 months and it is still not resolved. Mtn has now come back to me with the scenario that the store in question is a franchise and does not run under the MTN group policies and procedures, which to me seems ridiculous and that they cannot reimburse me back my money for the damaged nonconforming phone which they supp**** me and neither can they compensate me for my losses incurred, however they are prepared to reimburse me with R500 airtime and 25 gigs of data which does nothing to resolve the unnecessary financial woes that MTN's poor service has resulted to me and to say I have not got from them. And to make matters worse, instead of issuing me with a functional conforming device, MTN issued me back with the same faulty nonconforming device which is of no use to me and just continues to pile onto the unnecessary woes resulting from MTN and their pathetic service where customers who made MTN where it is today, but have no value to their value-added chain. Now I am stuck with a phone which they had for over a year and is still nonconforming. What do I do? And, even when I did explain the value of my phone for my job functions, how do I comply with my job which now will most definitely be at risk? I need someone at a level of authority who is able to resolve my issue immediately as I am in the process of proceeding with legal actions.