1Gig of Data Gone in 20 Minutes for a whatsapp update.

I loaded 1 Gig of Data this morning and within approximately 20 minutes it had disappeared and when I called their customer service I was advised that My Phone is a Lamborghini and that it uses more fuel than other cars. I then asked them to look into what had used up the data and was told that It didn't even reflect that I had just loaded data. I was then directed to my nearest Vodashop. At the Vodashop they were also shocked that 1 gig would just dissappear so quickly so they called Vodacom and they just said that I was downloading stuff on the internet which is very untrue. They said that apps which I had been downloading since the 29th of April had now started downloading again, bare in mind that my phone has very little space to download any apps. Why would my phone also wait until today when there was data on the phone the entire time prior to the recharge. I use an iPhone 4s by the way and have been since about 2012, so It would be safe to say that I know the phones tricks and how to save data on it. The previous 1Gig loaded lasted for about 24 days. So a better excuse please.