last October we had HDDR ressies for the first show on our arrival night (bad on my part.. but we were supposed to be there by noon)..
we got caught up in traffic due to a bad accident on i-95... we literally sat for HOURS.. I started calling dining around 2pm knowing we weren't going to make our reservation..
we were easily moved to the next night... then, the next day, DD caught a nasty bug and could not leave the room... called Dining around 4pm.. and we were AGAIN accomodated.
We were never charged a penalty (even though we were in the 24 hours), and were rebooked both times easily.
So, things DO happen.. keep calling... but the besst trick is to call FIRST thing in the AM, b/c that's when the bookings that were cancelled the day before are opened up.
Good luck!
It's a great show! You'll enjoy it!