Mtn is a scream

I received call from Mtn early this year September offering me a deal that I will end up paying R159 that was supposed to be a once off payment and to my surprise the debated R300 this month and when I call in for clearty they are taking me from pillar to post. When I asked them to counsel it for me they said I need to pay R430 cause I'm on a 26 month contract with them which I have not agreed on.