Data deplete on 3G-card But No Connection

I purchased 1Gig data for R160 for my 3G-modem, i use it to connect to the internet on my laptop. Then i activate the modem and it shows connected, but when i go to google it wont connect, giving me a "no internet connection error messages". I didnt use the internet, couldnt access my emails or download anything, but when i checked my balance it showed 390 MB off of the 1GB. What took the data, since i was unable to connect to internet? It cannot be any background apps because my laptop dont have any apps other than google, unlike an ipad/notebook, or smartphone etc.