I was told today that it is possible to go to Immigration to change your visa exempt status, if you have more than 21 days left before expiry, to a Non-B visa IF all the documents are in order? Has anyone done this and is this true? In other words not leaving the country.
TLDR : Answer Summary
It is possible to change your visa exempt status to a Non-B visa without leaving Thailand, provided you have more than 21 days left before expiration and all required documents are in order. However, this is subject to the discretion of the immigration officer on duty, and the availability of this service may vary by immigration office. Some users have successfully done this in locations like Jomtien and Samut Prakan. It is recommended to check specific requirements at the local immigration office.