Overcharge without explanation, no feedback on complaint

My cell phone contract is R189pm + VAT. Last month I was charged R2 800 due to Vodacom *****ing my data and without me knowing it I went online out of bundle. The data was replaced but yet the amount wasn't replaced in my bank. I logged a query with Vodacom a month ago, still no feedback. I monitored my data and air time usage during November. I did not go out of bundle once, yet my bill was R492. I called this morning to log yet ANOTHER complaint (not truly believing that I would get any feedback from the high and mighty Vodacom, but still I tried). I was holding for more than 5 minutes listening to irritating adverts and elevator music, only to be cut off without anyone answering.