Cancelled Service

Good day. I called Get More Cellc in August for cancellation of service and the agent who assisted me informed me that id get a call from the cancellations department within 30 days which didnt happen, i called again and they apologized for the inconvenience, i then recieved call from the cancellation department on 5 November to cancel, however they still debited from my account on the 25th. I called Cellc today to confirm if it was removed from my statement and regrettably so its still included in my account due for payment in December. When i call GetMore they tell me they debit in arrears even if ive cancelled my service with them!