Cell C

I am so disappointed with Cell C, I had a contract of a phone, after I finished paying the phone, they offered me Bundles for R45,00 a month which I pay on the 25th of every month,The contract I fully paid long time ago but they keep debit my account, I even had to change the Bank just for that , yesterday I was looking at my Credit Score Cell C says I own them R140.00 for what when the contract was fully paid early in 2017 already? Last month I even made a payment of R100.00 because I don't want their **** to mess my credit score but Still they say I am on arrears, Whenever I call them to cancel these Bundles they will always say I must give them my numbers they will get back to me but They dont.