Unable to close my account with MTN due to *****

In December 2020 someone did ***** on my account. It was sorted out after 3 months. In June 2021 again the same ***** took place. In April 2022 I then got calls from Nudebt that I was handed over to them for my outstanding balances. I requested from MTN Legal to send me my statement, but nothing reflected on my statement. After about 50 phone calls, I was told that their was a payment for June 2021 that was not paid. It was once again the same ***** that happened in December 2020 that happened again. Once again emails were send to Mtn Customer Services and Mtn Legal, phone calls were made. Nothing happened. Now that I want to cancel my account with MTN they indicated to me that I cannot cancel the account, due to the outstanding amount. PLEASE HELP