UNSATISFACTORY SERVICE. MTN ARE ********

I have a contract with MTN and I had cellphone insurance with them as well. I cancelled the cellphone in November 2020, however they are still billing me for it. I have called and emailed numerous departments within MTN, however they have been making me run around in circles for almost a month now. They have admitted in emails and on phone calls that my insurance was indeed cancelled, and they have asked me to send my invoices to show that I am still being billed for the insurance, and I have done all this, however they have blocked my line because I apparently “owe” them for the insurance and now they are threatening to have me blacklisted. I am so unsatisfied and exhausted as a customer and I am extremely disappointed in how they have handled this matter. They are doing absolutely nothing to rectify their administrative error and I am suffering for it