Extremely bad service

Good day I've had a contract with mtn for 2 years I missed 3 payments but I cleared out all outstanding payments, and wanted to close the account I paid the last amount in January of 2023 but it still shows on my report that I owe them when I called the call center they sent me in circles I just want a letter of payment which they refuse to give me as this is making it extremely difficult for me to move on, mtn is by far the worst network provider