I'm flying to Bangkok next week with Indigo Airlines (ams-mum-bkk) (one-way). I want to prepare for my DTV (deposit enough cash into my Thai account) and marry my fiancée at the end of the year. I want to take advantage of the first 60-90 days (60-day stamp / 30-day extension). This is where the uncertainty begins, as Indigo's support is very unreliable and I can't reach the check-in counter. I don't want to get into trouble, but I also don't want to waste money unnecessarily with onward tickets that aren't accepted or bus/train tickets that aren't recognized either. As I understand it, I can't use the 90 days without buying a ticket I wouldn't use. As a European, there don't seem to be any "cancellation" tickets; as I understand, that only applies to US citizens. Do you have any tips on how best to do this? Is it best to fly to Malaysia? Or are there cheaper options? Is it possible to buy tickets through Expedia? (They are cancelable or flexible).

And another question: is it still possible to get a DTV from a dentist about braces?