Poor customer service

I have been battling with MTN from the 25th of April to get a letter indicating that my account is not in arrears. I called their customer care they referred me to the branch. I got to The Grove branch in Pretoria very unhelp full they said they cant assist me I need to call the customer care line. I called the customer care again explained that I being send from Pillar to Post a lady advised that she will log a ticket for me and their admin team will send the letter via email within 2 to 48 hours. On Monday the 2nd of May 2022 I called again to follow up I was on the line with a consultant who advised she will speak to her manager asked me to hold. After holding for 20 minutes the consultant dropped the line. I called back again and another consultant advised the my reference number that I provided her with is still open and it takes up to 72 hours later the evening I received a sms my case has been closed with no letter received by MTN.