the worst service

I went to upgrade my cell phone contract I was going to be 4 months early they said I would pay R86 which I was fine with Rosemary also said if it was a lot more she would wait but being R86 I should upgrade now. So I do I get my statement last month and they bill me R406 I phoned and complained to Rosemary she said she will look into it mailed her daily with a response of she waiting on answers from her boss a few days later she said cause it is her error autopage said she will be liable for the error and said they will deduct the money from her I get my new statement this month and again they have deducted the R406 they owe me now R600 at least for there error and still nothing is being done. I wanted to give the phone back and wait the 4 months just so I don't have to pay the 406 bit now again hasn't been resolved. I've been with autopage for a number of years now and this is pretty much going to be the last with this very bad service. I want my money back why must I pay for her error it is not right.