data disappearing

my daughter has a wifi router that is allocated 2 gigs of data per month.<br> the data is depleted after 2 days of the new month.<br> this has happened for two months in a row.<br> vodacom cresta was approached and they were not at all helpful.<br> my daughter uses an iphone 5. she was referred to the istore. the istore personnel checked all settings and could not find any problem.<br> <br> vodacom service sucks!!!