Yes, thanks for all the comments - we're home now, and will call - we've been on the road for awhile. Didn't want to call then, because half the time, we have no consistent cell, and after half a discussion, we lose service and have to begin again.
Yes, you're right Mr Wizard - it's not a phone with apps - it's a hotspot WIFI.
So, should have some kind of answer from Verizon tomorrow. Good idea to check the towers - we're been all over, but certainly know where and when. We have a travel log that tells us each day - although I doubt if it will be that complex or require it.
I'm less concerned about the actual costs, as the answer - why does my bill jump so high with out me using more time/service a month. Don't mind paying for service if I use it, but am a little picky about paying for a mistake.
Thanks you all - will follow up when I know something.