We didn't have any problems with boxes, but we definitely had problems with UPS. There have been a few times where we have had no trailer for 4-5 days, and at an ESFS store that's not okay. We had probably 12-14 pallets of boxes and nowhere to put them so we had to just have them anywhere we could fit them in the SFS area. For a while, getting around our SFS packing area was like trying to walk through a jam-packed storage closet.
Then we've had issues with them just not coming to pick up rush orders.