The chatter about MobilityPass being a rip-off-firm is continuing, and I have not seen a single positive post about them yet. In retrospect, I got lucky, because all they got out of me was the cost of the modem, and since I could not get that to work with them for two months, I never got around to getting as far as usage charges.
Here is a good summary post so you can see other horror stories.
Here is another one. The horror stories abound.