Doc Stephens, REALTOR
That being said, I agree with Don Tepper... I often do, his advice is spot-on (thumbs-up from me). I'm sure that your agent has been meeting the same frustration in calling the listing agent. There may not be any additional information TO know... but if you think your agent hasn't been working hard enough to get you those answers... contact his/her managing broker, and see if you can stoke the coals a little.
I had a foreclosure in May that had an accepted offer due to close in 30 days. The title search revealed an unreleased lein from 1998 from a bank that is no longer in business. They pulled the property from market cancelled contract and then obtained a release. Just relisted 10-15-12
I agree with both of my colleagues, before taking matters into your own hands, contact the managing broker and express both your needs and frustrations to them. It is their job to supervise the agents under them and unless they know of a problem, they can't fix it.
If the managing broker is just as helpless as the agent, then at this stage of your transaction I guess it wouldn't hurt. If the listing agent however gets a call from the managing broker, if they are the source of the problem, chances are you'll get a better response via this route then calling on your own.