I had a contract cancelled last year after I returned a router at Middelburg Mall MTN South Africa after 3days as it wasn’t working, I paid up everything but still my name is Flagged on my credit report as missed payment

I had a contract cancelled last year after I returned a router at Middelburg Mall MTN South Africa after 3days as it wasn’t working, I paid up everything but still my name is Flagged on my credit report as missed payment. I asked them to update this on my credit report, asked them mtn collections to provide me with a paid up letter, a supervisor at the Middelburg mall branch Rudi promised to make a follow up on this but till today nothing has been done. Please help me with this regard, please find attached screenshots of report and conversation with Rudi Ngobeni the supervisor