Cellc complain

I have been a customer for cellc contract over 2 years earlier this year I canceled my 2 contract with them because it has ended I told them the reason I'm canceling it's bcoz I also hv 2 new contract that I took in August which was like 5 months ago so I wanted to focus on the new 1,my contract was canceled and I paid a balance of 1260 come month end I checked if it has cleared it showed that the account was in arrears I thought thy will update end of March bcoz I paid late but even today I tried calling cellc I was told I owe the R36 I paid it hoping it will clear everything now the account still says n arrears called cellc more than once but nothing I'm so disappointed and the fact that I still have 2 contract with them makes me want to cancel but I'm afraid thy will do me dirty again