Successfully extended until 30.11 WITHOUT embassy letter.
Chiang Mai, Promenada mall. Last month I got the REGULAR 30-day extension of my single-entry TR visa, stamped until 26.10 (so I didn't use any embassy letter, also because my embassy wasn't release any).
Last week I went to the immigration office to get the extension, but they turned me away because of no embassy letter.
I gave it a try again today after reading some posts in here saying that at some IO embassy letters were no longer needed and I successfully got stamped until 30.11
Didn't have to pay anything.
Again it seems like a hit-or-miss sort of thing. And apparently CM is a lucky one.
TLDR : Answer Summary
A user successfully extended their single-entry TR visa in Chiang Mai without needing an embassy letter, despite initial setbacks at the immigration office. The extension was granted for another 30 days, illustrating that requirements may vary by location.
