*ROOT NEEDED!*
Since the release of android 4.1.2 a change has been made and your carrier will recognize if it's tethering or normal internet traffic and if tethering it's not included in your plan they'll apply addictional rates. After a month of google research i found a thread on the official android support forum where a user posted the solution. Free Tethering Fix will help you applying this fix automatically at every boot, so you'll not be charged of other fees for the tethering traffic.
Link to block paid tethering from vodafone website http://goo.gl/ks68tJ