What Cell c is doing is *****. I want my money back

I cancelled my contract with Cell C last year October. I was paying less than R300. However Cell Cell has been debeting R710 after I have cancel not just that they are debeting me ever more money. I want my money and contract cancel.

When you call the customer care number you get through to an agent who will transfer you to "the billing department which the number does not work Contract number:*** ID. ***