No response and general poor service!

MTN has become pathetic in their service. I have been a customer for well over 20 years and they dont even have the decency to address complaints. I have given up on my last complaint as i have not heard from them in the last 2 years. I have upgraded my wifes contract in May 2021 with a data contract and have since been loading airtime to make calls as briefed by the salesperson. Since the 23rd February 2023, she cant make calls although there is airtime reflecting. The customer care official now tells me that it is a data sim and thus we cant make calls and will not be able to access the R200+ airtime that was loaded. It was fine for the last year and 9 months but now there is suddenly a problem. No one from MTN seem to take us seriously. To whom can we report this so that someone can intervene as their customer care and complaints email is useless?