posts say you need to go to the immigration office. Not the main immigration in Bangkok.
If you’d have done some research that didn’t include Facebook groups, you’d have seen very quickly that it needed to be the local immi office for your area. Better luck next time.
Yikes people. The exit ticket doesn’t have to be a flight. I’ve used bus tickets and train tickets before. No where does it say it must be a flight. It must however, be a ticket to exit the country.