Paying for what

I called the care centre yesterday to query why I'm been charged for a whatsapp bundle but my what's app is using almost, 700 mb of my data pm was told it's not activated on my account and them moment later told that it is and I only used used 500mb of the 1gb I then told the guy how is that possible cause I've used already 700mb this month that was taken from my bundle my data management app worked it out he said they would get back to me but I haven't heard a thing in a few days what can I do