Here's what I was told by UPS a moment ago (delivery date has slipped from 9/22 to some unknown date):
It shows that we have a contractual agreement with some shippers, which limits the amount of packages that can be handed over to UPS on any given day, when this
amount is exceeded, as in this case, the packages may experience delays. We need first to complete those packages that were given to us in previous days before we can export those that were recently shipped. My best advise is to keep on tracking the package on ups.com for further updates.
I'm very disappointed, as I'm traveling for a month beginning on Monday (9/26).