If the property is rented out already, but the agent didn't change it in the system yet - not calling is most often the case - not that it excuses the not calling...
What to do? - Pick a good rental agent working your area and the aggrivation of being ignored will go away.
Hope this helps,
Beachfront Realty, Inc.
Remax Advance Realty
You need to have a professional Realtor working with you. In your case, one that specialize on Residential Rentals on the North Miami Beach area. Give me a call so I can help you or send me an e-mail.
Miami Premier Realty
Sometimes Listing agents are there to negotiate, But most frequently they do not deal with buyers/tenants. only seller/landlords.
That's way we as an agents try to specialized in one field, Listings or Selling/rentals.
If you try to deal directly with the listing agent and you are not the type of renter the owner is looking for they will keep you on the side for days or weeks until they decided to give up and rent the place to you or reject your offer and deal with other agent customer.
I would highly suggest you to get an agent and work directly with that person.
Good luck. make sure you hire someone in your area, because i know agent working from Boca Raton to Florida city.
One Sto Realty