Its difficult to cancell an expired contract with Vodscom

Its very difficult to cancel a contract at Vodacom. My contracr expired and just found out that they were still charging me so i asked them to cancel it. Was yold i failed verification questions and then told to go to one of the stores with my ID. I drove to the store and was told thwy cant help me. Im so angry. I then called the call centre and spoke to the lady who told me that i was not supposed to go to the store and my they need to escalate my problem. I then asked for complaints department and was told Vodacom does not have one.