I complained about it and they said "it's always been 500mb" but I don't think it has. It's only the last 2 or 3 months that I've been getting warning messages saying I'm about to go over my limit of my "unlimited" data. I've had an iPhone since the start of 2009 and never had this problem. What annoys me the most is they still call it "unlimited" data. If 3 weren't really shit with their network coverage I'd move to them in a flash.