The issue not resolved after complaint

I have a contact with cell c and I am paying for an an instalment more than I am suppose to. I complaint before and I was told to go to the branch but the issue was never resolved instead the consultant told me head office said she is to pay me that extra R30 from her pocket every month. And more over I pay for data I buy every month even though I was told my contract has a limit and when I want to change, they say I must wait end of the month. All these details the person who helped me did not explain to me she even called the call center of how the contract works only when I came to complain, she said she did not know yet she sold me the phone with no transparency whatsoever, now I am stuck with bills I did not agreed upon and no one seem to help at all. I called cell c costumer care and they also send me to the cell c shop who are also unable to help me. I do not want to pay any extra charge on my phone that I know nothing about, I want cell c to remove the extra monies I am not suppose to pay please.