Abnormal Bill and not refund

I was billed a ridiculous amount of just over R7 000 data usage which I queried for the month of February 2016. This was apparently due to out of bundle rates. Which is odd since I only received the warning of high data usage literally on 29 February 2016 and no warning of being out of data. This despite the fact that I had carried over gigs of data from previous month and added additional gigs of data to carry me to end of month. I know my bill historically goes to just around R1 500. This is over four times that. I looked at the report and something was off like high data usage at times when I am either sleeping (during the AMs) or commuting or at home (I have wifi so no reason to be using data). The itemised report shows my in bundle data being depleted but what has been depleted as in bundle does not balance back to how much in bundle data I actually had. My query was taken up and eventually received a phone call stating that Vodacom is not accepting liability and the billing was correct...but they will refund me almost two thirds of the amount as a \gesture of goodwill\" within 48 hours from 7 April 2016. This has not happened. My bank account has not reflected anything."