Vodacom cant tell me why they taking my data??

I am very disillutioned with Vodacom. I have a pay as you go cell package that requires me to recharge when my airtime or data runs out. Over the past four days everytime I load airtime of any amount, It disappears within 10 seconds even though I am not using my phone for anything other than whatapp. All other mobile data options and app store options are turned off and have been for a long time. I contacted Vodacom customer care and was told they would look into it. In the mean time I have no access to my phone except when Vodacom are taking my hard earned money from me????? Anyone reading this please take care as Vodacom are not interested in your hard earned money.