If you've got a week or two spare have a read of this http://community.giffgaff.com/t5/Welcome-and-News/Unlimited-Mobile-Internet-We-need-your-feedback/td...
Do some people tether? Is this the problem? I thought the Giffgaff sim blocked it? How do they monitor? and what happens to the idiots who do tether?I would like to have the option and pay a tad more than £10 to get tethering.
Also, what does giffgaff expect people to use the unlimited data for?
Especially with your usage do not worry at all with your internet usage
all the best