Unauthorised upgrade

I had two data lines with usb modems that i cancelled after my 2 year contract expired. I was given a cancellations number( ********** ), to call, and i was required to give notice of termination a month prior to the expiry date, which I did. I was given a ref. no.1- ********** ********** . A few months later i noticed that i was still getting a bill from Vodacom, and i went in to the vodacom store at Baywest Mall, where i was advised that one contract was terminated and the other one was upgraded by the consultant (Mr. Mteto)that helped me when i called ********** . I was then asked to forward an affidavit and other documents to this e-mail address ********** i did on Monday 29 May 2017. The contract line in question ( ********** 080), was by now 3 months past its termination date. To date i have visited the vodacom centre in Greenacres , but with no success. I have not had any kind of response from vodacom or their foreinsic department regarding this matter, and they just continue to take money from my bank account every month for an upgrade that i did not ask for as i now have wifi since beginning of the year already. PLEASE HELP OR ADVISE ME, AS I DON'T KNOW WHAT TO DO ANYMORE.