Vodacom
Billing for Blackberry BIS data

I am a subscriber to Vodacom Blackberry BIS for the last few years. Recently i noticed that I am actually paying for data usage. I went to Vodashop to enquire, and they told me to phone accounts. BIS is activated and data should be free. My account were debited for the last few months as follows (3 months shown):
Data Usage September R70.92
Data Usage August R90.47
Data Usage July R58.55
Could I please get a full acceptable answer whether BIS is free or not? I really is poor service if your own VODASHOP tenants don't even know the answer.