Simple answer is know your billing password (what WireFly calls a PIN). I had this happen to me yesterday, but my order just went back to pre-order while I got my PIN reset by Verizon. Pretty stupid of them to cancel the order though.
You can report them to the FTC and the BBB.
I just saved my receipt that shows the $199 price so hopefully I don't have any issues. But I won't know unless I'm in the first 400 orders since that's all the more phones they have confirmed.
There is no way I'm giving Verizon another $100 voluntarily. Especially after having to pay $30 for the privilege to change phones. Hopefully the new rumors mean Newegg and Wirefly will ship within the next week.