Punished for settling an account by having to pay DOUBLE

Apparently paying up your Cell C contract is a punishable offence. In January my statement shows me an outstanding balance of R2499 for the account to be paid up which I paid. Later on in January R599 debited from my account despite me having paid up the R2499. At the end of February an additopnal R1843,65 debited from my account. So I have now paid DOUBLE the amount shown on my statement initially which was stipulated as the amount to pay up the contract and Cell C feeling like they have shares in my bank account to be debitting me left, right and center. I want my money back NOW. How on EARTH do you punish customers for paying up their accounts in full?