charged the wrong price

I upgraded my cellphone contract on the 27th of December 2015. When i was in the Cresta store, i asked to be upgraded on the same contract with the same amount of call minutes and sms and 500mb data. I then asked the salesman if he could put on the 2gb data as a top up every month as this is what i had on my previous contract before the upgrade. Before i had asked him to load the 2gb data, i asked what the price was and was answered with \R149 same as what I'm paying now\". My wife is a witness as we signed a similar contract for her and she was sitting next to me. I still did research with Vodacom to see who was cheaper with the data. I then agreed upon this and asked him to load it. i still signed another 2gb data for my father in law which cost R99. I received my new statement on the 24th of Feb 2016 with an amount of R229 for the data. I then contacted the call center to discuss this issue. The first call i held on for 20minutes and was hung up on. The second time i got through i explained the story again and asked to speak to the floor manager. I was rejected the right to talk to the manager. Want these issued sorted out asap. The service is disgusting, i will not stand for it."