USED AIRTIME ALTHOUGH BOUGHT DATA BUNDLE

My daughter bought 40Mb data bundle. Vodacom used the airtime and left the bundle as is. the number is ********** 786. On calling 111 they say it is a small amount and that once used it is gone. Vodacom randomly does this to people. If they ***** R10 from 25million customers they have 250million. They randomly take of 30 to 40 rand airtime from my account. I wonder if they get audited for the small amounts that they *****.