I work at Rapid Realty and I always return my calls,emails and text messages that my clients send me. I take my profession very serious. I can't speak for other agents but our team at Rapid Realty 958 Lafayette Ave Brooklyn, NY 11221 feel a great sense of empowerment and love to come to work.
It can be two things happening; 1- the apt is rented, 2-the agent is on vacation.
You can rent apts from any agent so I suggest you to look for other agents that are available when you call.
Best of luck
You can read their recommendations and explore a listing of Brooklyn agents here: http://www.trulia.com/voices/directory/Flatbush_Ditmas_Park-
Hope this helps,
Ali, Community Manager