You need a parabolic dish surrounding your USB 3G dongle, 3G modem or a 3G phone (iPhone included) when at home or outside. To make it simpler, a kitchen strainer and aluminum foil can also do the job pretty well in providing a significant signal boost.
Watch the Evidence/HowTo do it in the Video:
So next time you face issues with that dirty service provider, you have nothing to complain with after using this trick. But excessive exposure to RF (including 3G, WiFi) can have health affects. Take proper precautions.