Bad service

I got a new contract about two months ago which was load incorrectly, I asked for the flex @ R599 but I was debited R728, I went back to the Northgate to query and was adviced it was loaded incorrectly and would be corrected and refunded. That was 2 weeks ago, I've called them and was told the manager would call me back, I am still waiting. I really need this fixed I don't want to be paying extra unnecessarily. I really regret going to vodacom and hate the fact that I am stuck with such poor service because it's a 24 month contract