unhappy client

I had an account with Cell C and it was handed over to MBD i settled the account last year, i requested for a paid up letter but they took longer so i decided to contact Cell C and they told me that they will contact MBD and request for a paid up letter for me but luckily i received the paid up letter in few days and i informed cell c then they told me that the process to clear my name will take a month and that was in January but till today that account is still appearing on my credit report as an account that is in arrears, i tried to call cell c again last week and they told me that there's an agent that is going to give me a call in 48 hours regarding my account but still nothing, i called them today and the consultant just told me that I'm still in arrears, i mean after 3 months they are only telling me now that the account is in arrears but i have a paid up letter from MBD.