From what I've seen 6 month applications are getting approved. Depending on pricing, they can be pretty cheap. I saw Muay Thai Fever posting lots of DTV approvals. Maybe hit them up?
Are you looking to study language and end up being able to stay in Thailand because of it, or stay long term in Thailand doing an activity through DTV? Depending on your goal, one path is ED, one path is DTV.
From my understanding, you could get rejected with walk-in's but would not pay / not loose the money from the application. But with online applications, it's possible to loose the money if you made a mistake in the application. There's a French guy who just recently had to pay again because of this issue.