MTN Paid up Letter

I had an account with MTN *** which I paid up, in January 2022. I am struggling to get a paid-up letter from legal. I have since requested it in January and made a follow-up in June with no response. I need the letter urgently because on my credit is reflect as like i am still owing them.

I send many emails to MTN and called many times, still no help. MTN has a very bad service. I hope hellopeter you can help me, i am struggling because of people failing to do their simple jobs.