Telkom extended my LTE contract without me requesting an upgrade

I am unable to cancel my contract which was due to end 31/10/2017 - the call center incorrectly upgraded my contract in Feb when I called to only increase my monthly data package from 50g to 100g in 02/2017 because the LTE routers they provide use up more data than the actual user account (this is a common complaint). At the time of calling I double checked with the agent that this was not an "upgrade" as I was set on ending my contract and using a different service provider as the website gives out false information about data coverage, meaning I cant use this when I travel to a different location, which is why I signed up in the first place - but nothing was done to rectify this, even thought they admitted the problem. I am unable to get their error sorted out and the staff keep promising to call me back. If I cancel my debit order they will unfairly have me black listed. This is *****