Unauthorized Debit Orders

I recently cancelled a data contract with Telkom, within the 7 days cooling of period. The device was returned and to my surprise it has not been cancelled. i have been calling since the middle of July to have this resolved, and no one can help me. I am paying for a service i do not have. Every time the call center advises they are escalating the query, but nothing get done. no one knows what they are doing , and there is never a manager to speak to, this is the most *********** unorganized organisation..