Impossible to cancel a Telkom landline/ADSL

why is it impossible to cancel a Telkom Landline/ADSL - I cancelled my contract at the beginning of December 2018; Telkom make you jump through hoops; you can't cancel online but have to online on a really not user friendly system. I phoned numerous times to confirm that my line had indeed been cancelled. Eventually I received an sms confirming that my Telkom Landline/ADSL line had been cancelled effective 3 Jan 2019. since then I have been billed monthly with the account increasing every month. Repeated phone calls to Telkom yield no results; in fact the one call agent recommended I "just pay the account" to which I asked if she would pay for something/a service she did not have or had not received! I have subsequently been handed over. Forwarding the confirmation SMS; all the emails I have sent requesting them to reverse all the charges from 3 Jan 2019; every effort I have made to try and resolve this matter; to the agent/lawyers handling my case have also not resulted in the line being cancelled. I have now again been invoiced with another month added. Apparently there is now another agent/lawyer as I received an sms notification. the number provided gets cut off every time I try to phone so am unable to reach the person I need to contact. I am truly at my wits end trying to get this resolved and I truly cannot accept that I need to pay 7 months for a service that was cancelled effective 3 Jan 2019!