misleading

I went for my upgrade and I was told by the consultant she was going to close the open line I had and would just be billed a fixed instalment every month of R299. Last month MTN debited me R3000 and something which was not what I signed or agreed to. Now I have to pay bank charges to standard and get a bad credit record for something I was not awhere of. When I went to the consultant to complain she logged a incident and said she would get back to me with in a week it's a month today and she never did, when ever I phoned she is never available or she's not in work. I can't afford to pay for something that was not my fault or something I was told I felt that I was mislead by the consultant