Router cancelation pending

I am so disappointed with how mtn is handling my contract with them.. It's been +-3 months since I've had a query with the package I took but it seems they can't resolve the matter.. I've been so consistent with how I communicate about the matter until today they threatened to take me to credit of bereau.. I've stopped paying because they have bridged their contract.. They give me wrong package.. I had to pay R123 or so for 20GB but instead they gave me less internet then said I have zoom, educational, music streaming.. Of which I've never agreed to such I don't use zoom am an out surance pointswoman how on earth will I use zoom data for? I asked for them to cancel my contract but I can't seem to get them to assist with that... I won't allow to be blacklisted for their own carelessness.. Please can I be assisted accordingly am tired