Vodacom data disappear

My data disappeared. I have a wi-fi router with 10 gig data. Before the month end all my data was used up! Which was very strange. I loaded 1gig. Within 1 day it was gone!! I reported it to Vodacom. I loaded another 500mb...within seconds gone!! I reported it again to the customer care center. I loaded 500mb and within less than 2 min it was gone. The guy at customer care admitted that it was very strange. I only checked my emails. I have no games or other apps on my desktop. All apps background data is restricted and I restrict all updates as well. Since the call centre did not call me back as promised, I reported the problem online TWICE. Not even a reply from Vodacom. They ***** data and get away with it.