mtn does not connect everyone

I renewed my contract with MTN in November 2014. Contract amount was R399 and R269. Total R670. Since December my debit order has increased to R800 till end June it is R1960.A limit on data was set by consultant. But my installment continues to increase. I spoke to the manager at the Somerset West branch who confirmed with the consultant a limit was set. The Manageress could not give me an answer as to why this was not done. She also made me feel like I was lying. Being a loyal customer for twenty years she treated me with disrespect. She said I could cancel my account and go where I wanted. She also threatened me with court. I feel as if I am guilty of a doing something wrong. The consultant also did not explain anything on the contract. I want mtn to accept responsibility for there error.