stop taking my money

so I tried so many times to cancel my contract with cell c, since from June, I called the cancellation department so man times , they refused to cancel my contact , eventually around July they said it was cancelled. I stopped receiving the benefits and I was put on prepaid as I had requested, however Cell C has kept on trying to debit money from my account ever since, I call every time and they say they have cancelled my contract, however they keep debiting money from my account, when I call , I keep getting transferred to different people with no Help... I am totally sick and tired, why cant you let people leave if they want to leave since you have ******* services