I put together about 100 pages of information, including letters from my parents, all my bank statements, my supporting letter, employment verification, documentation, passport, etc., etc., etc. They didn’t look at one page. They tapped on the computer screen and said no.
unfortunately you need a lot more than that. You need to somehow “prove” that she’s going to return that’s the keyword will she return? Does she have a business that she owns, family etc. etc. it’s not easy, tried with and without attorneys. 
I couldn’t agree more Ryan. Tried several times with my girlfriend for vacation to USA. declined declined declined. I even appealed the decision with local government in Los Angeles who communicated with US Embassy in Bangkok to no avail.
Its just so hard because historically, many Thai (ladies anyway), don’t come back. They want proof that they will return. (Own business/family/own home/taxes paid etc.