I would be curious as what "Actually" happened. Verizon just doesnt take away a New Every Credit without the customer changing something on the account. Unless it was a billing system error, which in turn I am sure they would fix the problem as mention by simply calling and speaking with a supervisor.
I have had a New Every Two credit for $100 on one of my lines for a long time and it has not gone anywhere. You also have to understand that the $100 credit comes with specific guidelines, so as I mentioned above if you have changed something on your account it may have effected the credit.
Of course with your response, Verzion will certainly do better by letting customer like you go, I am sure they have enough customers already in their system that rudely deal with issues rather than effectively.! 