I used to work WDW reservations, so I can give you a few hints about priority seating calls.
First of all, this is peak reservation season (Jan-Mar/April) so the queue time is going to be a lot longer. Make sure you dial the dining number (407-wdw-dine) if you are only making priority seatings. The reason I say this is because during the peak seasons, they add extra agents to only take dining calls to help alleviate the call volume to the other agents.
Second, there is never a case of "forgetting about you", so hanging up and redialing will not be a good option. The call center is set up to automatically take the next call in the queue.
Lastly, the reservations center takes calls until 10pm EST (Someone correct me if I'm wrong on that!). If you call before that time, the agents do not go home until the "queue" is cleared.
I hope that info helps!!