I don't know if it's an option for you, but you can take them to a Verizon store. At least that's what my wife and I were told when we pre-ordered our phones at our local store.
You can only do that if you preordered in store, online preorders will receive return stuff in the mail (with the new phone) and can only be returned by mail. That's what I had to do last year with the 6 to 6s.