I've had this happen before, actually twice.
Call Amazon support and tell them you didn't receive a package that they claim was delivered. DONT deal with UPS, it's a waste of time.
Amazon will call UPS to verify, however Amazon has INSURANCE to cover these instances, so they will most likely replace it for you at no cost, unless it was above $100 or $250, I forgot the amount.
Just recently I ordered a few things and got the email "package delivered" yet, NOTHING there


Then a few hours later, door bell rings and its UPS. I think UPS has some "intelligent" software that can estimate when a package is delivered. Think about it, each time someone drops off a package to scan and confirm, that takes time. If they only have to do it once every 5, they can estimate when the rest will be delivered based upon time, conditions, etc.