Make sure you get your complimentary one month of free service from Verizon if you had your grandfathered unlimited data taken away. They will also give you 30 days to return your phone and restore you unlimited data contract. The best way to go about keeping your unlimited data is to buy your phone from Best Buy at full retail price and do the 18 months no interest financing. Will only run you about $30 a month and you wont be tied into a contract. Don't let Verizon profit from selling you a subsidized phone.
Also forming a contractual law suit against Verizon. If you feel you were not made aware by Verizon customer service when upgrading that you would lose your unlimited data, then feel free to reach out to me. I have a video recording of both a best buy/Verizon store upgrade experience without being made aware that our unlimited data was being taken away. Also have false information given to me via verizon customer service online chat.