Bad services

I'm very disappointed at cell i thought the issue of being charge after contract was terminated have been resolve because i have paid what i needed to but this month i get an invoice saying i owe 140 which is the charging for the debit order that i reversed since they were not entitle to deduct but i had asked cell c to resolve this because im not paying anything above what i have already donated,can someone senior close this matter cause im irritated right now if you have no right to deduct you cant keep on deducting and expecting people not to reverse im very disapointed at cell it use to be a company with high moral and very ethical but what they are doing now its out of this workd and disgusting ,no one should call me ,just write off the amount that you created yourself cause i wont pay anything