Complaint unfair black listed by vodacom

My name is Mongezi Lusu from cape Town. I asked vodacom to give me a settlement amount, at the start of October 2020. They gave me the amount. I paid the amount on the 7th of October 2020. They were suppose to cancel the contract and give me the paid up letter. I'm still waiting for that letter till today three months on the line. I was at vodacom today to to ask them to help with the insurance of the phone as my phone was ****** yesterday. To my surprise my name is label as a bad payer. When I asked about this, I was told that I still owe vodacom an amount of R 1622. 52. I know about this because at the end of October this amount was deducted from my salary, of which I reversed it. When I investigated further I found out. Someone from vodacom left out one currector when the payment was made in my contract. This simple means that my contract was never canceled. Then they billed me that amount I reversed because to my knowledge the account was settled. Now my name is black listed. I can't get the insurance for my lost phone. I can't get the paid up letter for the new house I busy buying right now. When I phone vodacom heard office I'm told to phone the cancelation department, the cancelation department will tell me to phone the account department. This is what has been happening since October 7, 2020. Even to day I spend whole day at vodacom, promenade. The last thing they did to tell me that they will phone me back or they hung up at me. The bank for my new home is still waiting for the paid up letter. My name is black listed. What must I do to clear my name. Please help. Mongezi Lusu *** ***