Contract not canceled

Three months ago I canceled my wireless modem contract that had already finished its 24 months requirement & also provided required documentation. But it still continued. Then on the 4th of November 2018 I visited Telkom store at La Lucia Mall & they worked on the system & told me that my account was charged to prepaid & all my November data was canceled, including contract. Therefore my month end bill was to be pro rata per the 5 days that I had already used some of the allocated data. But to my surprise, I was charged more today. When calling telkom the billing department told me that my contract was simply renew to another one, hence the high bill. When I requested to be transferred to the department where cancelation will be done, I was informed by the consultant that I should go back to the store. Therefore the problem remains unchanged & my time & money being wasted.