Telkom LTE Cancellation issue - Telkom is quick to sell a product, but when they have to cancel no one can assist!!

Telkom convinced me that the LTE internet modem is fast and great. They sold me the product and it was delivered via a courier in April 2016. It never worked and we complained constantly about the bad internet. After confirmation from Telkom, informing me that we do not have coverage in our area for LTE, I cancelled this line in June 2016. TELKOM confirmed they received the cancellation and that it was done. In May 2017 we realised they are still debiting one of my accounts which I rarely use for the last year!!! I have been calling Telkom call center for the last four months DAILY and they are too *********** to solve this issue. They give me the same story every time: It has been escalated, a manager will contact me within one day. After one day I call in to find out what is going on, and they tell me that the manager made a note on the system that they spoke to me the previous day WHEN NO ONE HAS SPOKEN TO ME FROM TELKOM ABOUT THE CANCELLATION for the last FOUR months!! They seem to be very quick and helpful by selling products that are faulty and will not even work in some areas, but when you need them to fix their problem and cancel the line - they are too *********** and unwilling. I want this LTE line cancelled and the money I paid for the last year for a product that I did not use, refunded!!!