We used a
travel agent (different agency than the last one we used, both of which are Disney specialist agencies... no, neither of them was
Dreams Unlimited) to book the trip we have upcoming in 52 days, 12 hrs, but who's counting?

The first agent that we had assigned was one we were familiar with from several podcast episodes and came highly recommended. Unfortunately, like yours, she was VERY bad at returning phone calls & emails, and when she promised to call on a specific day & time, she virtually never did follow through. As a result, I contacted both the agent & the head of the agency via email to request that, since she was obviously too busy to be able to assist with our reservation as needed, would they please reassign us to another agent. They did so within 24 hours and the new one, while rather busy too at times, has always called back when promised (missed 1 call, but, that was because of an emergency trip to the hospital, that's reasonable!). We've made various changes to our plans as a result of what she's found/suggested, and has been very helpful. We're very satisfied, & still counting the days/hours/minutes/seconds til our plane leaves for WDW
Definitely, contact the agency & ask that you be assigned a different agent if you're having a lot of trouble. Remember, you can always take your business elsewhere, whether to another agent or even another agency, if needed. It's YOUR money!
Enjoy the magic, & good luck!