Robbing us blind

I have complained several time to vodacom about their data(whatsapp monthly data vs normal monthly data) Every month i buy a monthly whatsapp data ticket, and during the month i would buy normal data(daily,weekly,monthly) depending on what i need to use.

Now what these guys do is, even though you have a monthly whatsapp ticket, when you buy normal data and brows your whatsapp(videos/images) they use up your normal data as opposed to your whatsapp ticket data.

How does that make sense!?..i mean if i have a monthly whatsapp ticket why touch my normal data for anything whatsapp related. So now what that means is that while im browsing whatsapp, my normal data which i bought for other reasons is being used up, forcing me to buy more data to do whatever else i want to do.

That is ridiculous and it needs to be looked into as i feel its just a way of vodacom making more money off the public.