MTN POOR CLIENT SERVICE, NON EXISTENCE

I paid my monthly bill on time every month, paid late once but before month end paid as requested and again the full amount month end. Now getting SMS notify me to pay close to R3000!!! I wrote e-mail 14 April 2021 which MTN gave me a Reference number : *** and that they will attend. To date absolutely NOTHING!! NO MAIL, CALL OR E-MAIL, tried to call so many times with ABSOLUTELY NO LUCK,!!!!!!! This after so many years of upgrading and staying with MTN, I doubt if I will stay with them, they are not even worth the one star as the system would not allow nothing for Absolutely POOR CLIENT SERVICE!!!? But MTN can keep on reminders for my upgrade is due very shortly, HOW THE HELLLLLLL!!!!!