got my DTV approved in Hanoi using soft-power medical route...
- had my money in savings accounts. Which the lady at the desk thought might be a problem. Because it didn't have any transactions going in and out etc. But I wrote a short note explaining there weren't any transactions because it was a savings account. And also printed out a screenshot from my bank's website showing that the funds were fully accessible (i.e. not a fixed savings account or anything) and that was fine
- for the medical stuff, I showed copies of the paperwork I'd received from the hospitals I'd been to. Proving previous appointments, an appointment booked for when I flew back, and general proof of ongoing care in Thailand
- the bank notes I got from the exchange place at chiang mai airport. i was a bit worried because they weren't "perfect". But they were flat and didn't have any tears or writing/marks etc and she accepted them no problem
- it took a couple of days longer than the 2-3 days advertised. And I sent an email chasing things up. I was going to go down there in person and see what was happening, but then I woke up and there was an approval email in my inbox
Everything else was just the standard paperwork i'd seen you needed: proof of flight to thailand, proof of address in Vietnam, proof of address in Thailand, photocopy of my passport (picture page and the vietnam visa page), and the application form itself
It's also worth mentioning to be aware of the lunch break times there. I booked my appointment for 1.30pm and turned up about 20 minutes early in case it was busy or something. But it was shut for lunch, so I just had to sit outside in the rain like a plonker