Billing of data

On the 1st of April 2.3 GB was loaded on my phone. I called Vodacom that this was inaccurate as O receive 2.00GB every month. They retracted their mistake. Today the 6th of April, my data is at 800MB which is not possible. That is TOO much! I don't use that much data, and it always lasts me right till the end of the month. Upset and angry customer