Mine is a bit odd, I've got the "VMI WEB Browsing" pack - which is the Unlimited (500mb FUP) addon but they give it to me free. Had it for about 4 months - the previous 3 months I've used well over the 500mb
Feb - made 1.212GB of mobile browsing + data calls
Mar - made 2.741GB of mobile browsing + data calls
Apr - made 2.244GB of mobile browsing + data calls

So far this month I'm up to 1.5GB - my bill will increase dramatically if I get charged £5 per 500mb - currently my bills over the past 3 months have averaged ~£20 (just less than).

Edit: I've not had ANY text from Vodafone at all, no contact regardless of what I used per month.

Based on this article the 10% rule applies completely, my bill will go from £20/month to at least £25 - £30 per month!


Marlon