R 6000 for Data charges

I have been a customer for 9 years , I have faithfully paid my account without hassle, last week I was unable to utilize my phone, when I called the customer service desk , I was notified that my line has been suspended to due to excessive data , I was surprised by this , as I only use data for Whatsapp & google maps . The operator could not clarify what the data usage was she stated that I had to wait for the statement & to activate my line I had to pay 50% of the charges upfront.<br> 1. if you look through my payment history I have never paid a bill that was higher than R1500, so how does the charges add up ?? R6000 for data charges seems uncertain...<br> 2. What is the cost of the data on a normal level ??<br> 3. I expect a detailed review on the matter to be handled ..