Lawyers are also motivated by making money and I've seen some investors set up ridiculously complex structures. 

I answer my phone, and respond to all my emails and texts.

You really don't want to buy this liability if you aren't being paid for it.Either way, Seller will be stuck with disclosing the unpermitted work to future prospects which should be motivation to resolve the issue.

However, they took our data and never responded to any emails, calls, or texts! 

They are never the cheapest, but if you hire the cheapest you get to follow them around and add a job of micromanaging to your list of daily activities.CEO's of multi million dollar companies golf 3 times a week, shop for cars mid day, get suits tailored, hop a jet to fly fish, have perfect haircuts every week, volunteer at a shelter passing out food, get photo ops and make company motivational videos.

Write them a letter, track down their phone number to call and/or text and knock on their door.

Motivated buyers driving the area usually see the open sign and try to get in before the Open.

Texts to the the phone get forwarded to my phone (and I get an email notification).  

I enjoyed that mine was a one man band, and it was smooth and efficient, handled by email and short hand dialogue and simple resolutions.My eviction filings, so far have been "light weight," mostly gets people motivated to pay and stay.I spoke to a couple of firms, but they make it sound much more complicated and ugly than it has been in my case, so they aren't resonating with me.

Like @Sarah Kensinger said, I would surround yourself with like-minded people that have had success in the real estate industry to motivate you and teach you things you may not know!