1GB depleted in 20 minutes!

So I am out of data and decide to take up a promotional offer of R39 for 1GB for 2 days. With a little more than R100 in airtime, I take up the offer because it looked like a good deal. Twenty minutes later the data was gone and so was my airtime! Yes, I was on Facebook, but logic tells me that even then it is not possible to consume so much data that quickly. Having done my phone updates from a wifi connection earlier yesterday, I know that no updates were pending! This is a *******! Vodacom must think that their customers are idiots if they think they can continue fooling people like this! In fact, ICASA must be sleeping on the job here! I would rather be on a \slap tiger"network that values me than with arrogant fools who think they will always have a lion's share of the market even though they do not keep their existing client base satisfied! Why is data so expensive in this country anyway? If what you sold me is 1GB of data then I have used 5GB of data this month alone"