Vodacom overcharging me.. again!

Good Day

I contacted vodacom regarding another overcharge. Nobody followed up or contacted me to sort out the problem. They basically just told me they can do what they want and add more to the bill if they wanted. My bill was R611 with the tax hike last month which i understand but went to R638 for NO reason. No one can or want to tell me why!!?? Alot of my friends are complaining about this? I want my acc sorted out or someone must phone me.

Dewald