Completely overbilled with no explaination!!

My account was debited for the month of march and I discovered that I was way overcharged for something mysteriously called \DATA USAGE"(over R550!) <br> <br> I am so sick of Vodacom doing this because I have had many people complain to me about this exact charge! Despite the fact that within this month I bought 3 once-off 1Gigabyte data bundles in order make sure there was no way I would be charged for \""out of bundle\"" rates"