@Sam ********
okay IF your school is telling you how to go apply for a 90 day Non-B at the thai consulate in Vientiane that means they CANNOT provide the documentation for you to do an in country conversion from a tourist visa or visa exempt entry to a 90 day Non-B at the immigration office.
The documentation the school gives you is addressed to a specific consulate SO pick where you're going (or seeing as you have no idea, why not take your employers advice and go to Vientiane?).
Remember you need an appointment to use the thai consulate in Vientiane, You want to make an appointment for a Non-Immigrant Type visa at this link
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