I've used a Jetpack for years at home for internet. In July I went from 5gb per month to 28gb+ and am now over my 30gb limit. Nothing has changed, same computer, same daily activities.
How can my monthly data usage change that dramatically? Again, I have changed no hardware or activities. I use Facebook, email, and play an online game and have for several years now. I see no evidence of an unauthorized device connecting to the Jetpack.