Unhappy customer

I was having issues with multichoice last year about escalating charges which i was billed on my account after one of their agent had made a sale on me for WiFi contract. The matter was resolved after involving hello peter, i was told i will be paying R560 going forward, surprisingly last month i had to pay over R700 hundred this month they want me to pay R1000 for charges which i dont even know about. I am considering leaving them permanently .