Hurting customer

I used vodacom since i owned a phone, like forever. But today they showed me that I should trust anything about them.I wanted to cancel an account ,then they gave me idea to update instead, they said I should only pay the handset then they will only update the simcard and give me data only, I wanted to close account because I no longer want to pay too much. But today they increased my debt, and nobody wants to help me. Everyone promise to call back, I even exceeded call limits to vodacom. this time they showed me flames. I am so hurt by vodacom, I don't even know what to do where to go about this problem. They gave me the upgrade without full agreement now am stuck with a high payment. I payed the money to payoff that nightmare handset, Vodacom took it as monthly instalment. I am so troubled I want to cancel the whole thing. I visited vodacom shops to no avail. I asked to speak to guy who helped me to no avail. What should I do now.