Dmc *****ulently collecting a paid up cell c account

I had a cell c account that I was paying through css and manage to pay in full but I recently discovered that the same cell c account that was fully paid up with css, it is being collected by dmc I have sent them emails with paid up letter from css and cell c and I have called several times to ask them to remove my name n update my credit report as I do not owe them any money but still no luck and the account was paid 29 November 2023 but they are still collecting while the account is fully paid. Please update my credit report and remove dmc as I do not owe you anything