Verizon, if not all cellular providers, doesn't work like a credit card company, nor are they a bank. If they bill equipment to your account, it is expected to be paid in full on the next statement. If a salesman said otherwise, they should be disciplined and/or fired.
Your threats to post your rant on the internet/media will fall on deaf ears with Verizon and will not likely result in your wishes. If you wanted to pay for the phone in installments, you should have used a credit card from the beginning.
Your best bet from the beginning, assuming you bought the phone at a local store, would have been to go back to the place of purchase to dispute, and not calling customer service (unless they sent the phone) asking them to intervene. Customer service CANNOT force a store to take back a phone. If you read your contract, your options for resolution such as this are clearly stated.
I am sorry for your unfortunate experience and I hope it can be resolved in a fair/equitable solution. Good luck.