Un happy client

I have a challenge with cell c and their billing dept, No one is interested in assisting with my query but all they do is being quick with debiting my account, A sales agent sold me a special of R80 per month for 5 gig of data but was never advised that its an open line been struggling with cell c from April have all the references but no agent is able to assist, all i need now is the contract cancelled and they must stop debiting my account as they dont know what they are doing