UPS has always been very very good to me. When bumped, I have been called by UPS, so for me it wasn't a mystery, I knew beforehand (doesn't mean it will happen every time). If you can't make it, be sure to call and cancel as well.
Everyone was always very friendly and very awesome, it's was certainly a privilege to j/s on them. My QOL went up several points when I started commuting on them regularly.