VODACOM POOR SERVICE

I logged a complaint and Vodacom representative called me and never resolved my issue of them deducting money of the service that is not there. The guy that called said he will request their manager to call me and since then I have been waiting for the manager's call. I requested them several times to send me a letter that confirms that their service has been cancelled and was never renewed. I am not sure what are they charging me for?