data query

I have found that my data and airtime over last few months has been vanishing. Today 1st august 2015 decided to keep tabs on my account via *111# phoned into query and was refunded my airtime. So im sure this isnt the first time its happened and i would like to know what vodacom is doing to make sure it wont happen again and if they will go back and check all customers accounts. Seems like something really simple to do.