Deductions made with no reason and poor customer service

There has been error with my billing. I called through to the customer service department, and FINALLY a consultant understood my concern instead of giving me the generic response. I thought it was resolved, only to find out it's not because then R2000 was deducted from my available credit. When I called to enquiry about it, I was told it will be escalated to a manager who would call me back. This is was two weeks ago and no call received. I have to keep calling using my airtime and everytime I do call, I am assured that I will receive a call back. Which I never do. I've lost track of my many representatives I've spoken to.