they are supposed to file one, get a screen shot. If this doesn’t happen ask them for a letter stating you are staying there, including your full name, passport number, date of birth, home country (same as passport country)
Either buy a fully refundable ticket, can be to Vietnam or anywhere just as long as it’s fully refundable and cancel it after you leave on your flight
Or use a ticket service like onward ticket
They sell flights for about $14
It last about 24 or 48 hours from time of booking
Used to show a flight out of Thailand
Or take your chance when boarding
I have flown at least 30 times in the last 13 years and have been asked every time I didn’t have a return ticket, as I was living in Thailand I was able to get around it.
Last year was able to baffle them when asked, and they accepted my answer 🤣🤣
However I was prepared to go online and buy a ticket if needed
Ppl will say it’s fine or you will not be asked, however be prepared, I’ve seen ppl post they either missed their flight (not allowed to board, or had to purchase an expensive ticket
Try this as it has always worked for me & ppl I’ve taken to get one
Certificate of residence, ask the hotel where you are staying to do a letter for you, the letter needs your full name, date of birth, passport number, country of Origin/ passport, stating you are residing at the hotel & hotel address and contact number, take this letter to immigration and tell them you want to get a driver’s licence or bank account, They will supply you a letter in Thai writing & on that letter it will state it is for a Thai licence or bank account depending on what you tell them it’s for & will expire 30 days after date of issue, immigration office”s operate differently in different areas and depending on who serves you, if it doesn’t work in Bangkok, try another part of Thailand.