Whatsapp doesn't work over 3G,everything else works fine

A friend has a factory fresh, unrooted Samsung Galaxy S Duos, and except for Whatsapp every other internet accessing app works fine on a 3G or EDGE connection. She has un/reinstalled Whatsapp several times. It works fine over Wifi. She's no power user, so any solution involving rooting the phone is not an option. To clarify - there is nothing wrong with 3G or EDGE on her phone, since she can browse the internet and use other such apps perfectly fine. **Update** - She's on Vodafone, as I and thousands of people in India are, and no, Vodafone is not blocking Whatsapp for any reason. Searching for solutions on Google only leads to 'No shit, Sherlock!' type answers with genius level solutions like 'check whether your 3G connection is working' or 'get the latest version of Whatsapp'. So is there a workaround?