Many times the offers online cannot be seen by the CSR, and if you find a GOOD Offer online, I say take it. But the system has improved and they should see what you see. If you get the order confirmation and number, they will honor the offer. They must, or it is false advertising. They can't make an offer, confirm it with a detail estimated cost, and give you a confirmation number, and not follow though. I have found them extreamly fair. But if you point out an error on the web, they might not honor it unless you have a confirmed order.
At times Verizon does provide online special offers that I have found to be very good. But I had issues getting the order "pushed through early" until I was able to provide an order number and the Email confirmation. I have found Verizon to be very fair when there is an error on their part, and the deal is given to you and confirmed. Even if they must give special 24 month discounts. I feel 100% that there is never any attempt to deceive, but computers and people do make errors.
But as said, there are online deals that are better if you place them online.