Go and install some data usage monitor app on your phone and see if your phone use up 350 MB in 5 days. If the app detect 2 MB but hotlink shows you have used 350 MB, screenshot it and complain ASAP. If the app also detect 350 MB, then something in your phone is eating up the data.

Mobile data usually calculate on the fly by the service provider, rarely it will go wrong unless your simcard has been cloned. But new generation simcard that support umts/lte is difficult to be cloned. If your usage calculate is flawed on the provider side, definitely you are not the first to discover. This kind of issue can cause a vendor to suffer penalty and compensation.

This post has been edited by kons: Jan 7 2015, 01:01 PM