Customer Service was not able to help me. I just went in to the reservation system, selected the people in my group, and chose Hollywood Studios. It will tell you there are no reservations, but keep going back to the park choice page and keep trying. I found an opening for the day I wanted after trying for 20-30min (for our party of 5!). Openings do occur, but they will not be reflected on the calendar. You need to actually go in to a reservation and keep trying. Make sure you do not have any other park scheduled for that day. Epcot rarely sells out so keep that as your backup plan for that day. You can always reserve Epcot if you give up on HWS. Good luck!