Selfish and disappointing service

I owed R1040 and settled it this month. R300 last month and R750.this month. Each time I called this company I was told the settlement amount was different each time, I even requested for a manager to call me but no one did. So I settled my own way.

Now I'm bieng told I owe another R200 out of no where! I have a daughter who is turning 1, I'm not rich and I don't have much help. So I feel like I'm bieng taken advantage of here and I can't let this effect my credit. Please intervene as I'm out of pocket now!