I know the HEB area very well. I used to live in Southlake and did lots of business there in the last 15 years.
I am sorry, I know i do not specialize in the HEB area because I do not know where it is. But it seems that the Dallas , Ft. Worth agents don't either since one is offering to assist you. Were is the HEB area and maybe they can direct you better.
When you look in you papers for rentals it should say agent, when a agent has the rental, that same agent , if an MLS agent will or lets say hopefully should look up other rentals for you.