I didn't read over the whole thread, but I have the 30 dollar original sero plan. Heard about this asked customer care and this was their response. Apparently I can switch to sero premium if I like, for additional 10 which would give me unlimited mobile 2 mobile & navigation and if I wanted a 4G device it would be another 10 on top of that, to make the total 50 dollars. Here's a image of my ecare reply.
~Mike