Bad service and ******* deductions to my bank account

I had a contract with Cell C, after it has long expired they rock to my account and take whatever amount of money they want. This has ruined my reputation with my bank so much. When I call them they send me from pillar to post, if I am luck enough to find someone to take my call. Cell C shops in the malls also can't help me because my contract was over the phone. Just a warning to everybody to be aware of the way they make their money.