If you just want to block the data the easiest way is to go to Unlockit - APN Changer for your iPhone
on your iPhone. All the website allows for is to install a profile to the iPhone that has a different APN setting to it. To block the data you download a profile that has false APN settings so the iPhone can not connect to the Fido Data servers. The website has instructions for installing a fake APN and it is rather easy.
If you jailbreak the phone that will allow you to download unauthorized programs some of which allow you to turn off 3G and Edge. If you don't know what you are doing try installing an APN setting profile first.