There are agents, and there are agents...
If the TA is based in one of the store fronts, chances are you'll get a slow response. They cater mostly to those that walk in the store and talk in person.
The best TAs are the ones in the back on a central office. Typically you'll get those when you start off via the 800 number and ask for a Disney specialist.
Last August, I booked a trip via the TA, mostly because I wanted the Diamond pass (was driving). From the start, I lay down my rules about availabilty and who to contact if she was out or on vacation. She noted on the account that any other rep could make changes. Then a public offer was to come out in the end of August and she was to be out on vacation.
Still at 6:30am (her first vacation date) she sent me an email that she had updated my rez with the new public offer.