Cell C are *****ing from me by charging me more than double on my contracts each month

I wanted to cancel my subscriptions with Cell C as I had 6 contracts and as they started to expire I tried cancelling them. I am still however stuck with 4 contracts and one is pay as you go, but I pay R49 a month for some data. All the other 4 contracts is just under or just over R200 per month but each and every month Cell C decides how much money they want to debit me with. I stopped my debit order as I have tried to resove this on many occations. With my last contract I wanted to cancel, the quy who made sure I take up a new contract with Cell C, promised me that the issue on the one date bundle of R199 per month would be set to a fixed rate and a closed contract. Still nothing happend and now my lines are cut, while I feel Cell C is owing me money.