Vodacom billing you for whatever they want

I went to Tygervalley vodacom shop to deal with a billing issue. This after calling their call center. I took a double deal you know those ones buy one for the price of two. Now that the bill comes its not the case as I am being charged for the second one. Sitting there for 90 minutes the consultant that helped me say that I should not get billed for it. Yet there is nothing he can do about it I can only mail the head office. The manager sits at the back don't come to the front to deal with this mess NO. After all this it's clear that I was no closer to resolving the problem I walked out only for another sales consultant to applause the consultant that helped me praising him.