I just want to say KEEP CALLING!!
I call about three times a day (morning, noon and night)!
I rushed and booked our ADRs before even booking our resort (since it's Thanksgiving week). I was able to get the restaurants I wanted, but not always at a good time.
I've been calling and calling to change my times, even for as little as 30 mins different and I've been actually getting lucky!!
I'm still holding out for CRT breakfast, but I was able to get Le Cellier for lunch at 1pm!!
I just want to say, don't give up. KEEP CALLING!!! You never know when someone is going to cancel!!