Impossible to cancel a Telkom Contract - They just want to keep chargin

I've been trying since February to cancel my Telkom uncapped LTE service. I emailed the required form to the appropriate email. They acknowledge that they received it but never responds, not even to follow up emails. Then I called their call centre and reached Matsheka Tumelo who at first was very friendly and helpful, she asked that I forward the mail to her and even responded that she would make sure that it was cancelled. Initially, I thought it was the best service I received in a while but unfortunately, my internet is still working and now all of a sudden she doesn't respond to emails. The only response I received from Telkom is that I should expect a call to upgrade. Can you believe it!!! It seems impossible to cancel a telkom service. Quick to sell but impossible to cancel