@เตเต้ *****
Actually the question is wrong – because a „visa“ cannot be extended and will never get “extended”
Even when the paper pushing stamps stomping officers on Thai Immigration call it “visa extension”, all they do is extending a simple “stay permit”
As a “visa” is meant for use when ENTERING their beautiful country, it becomes invalid the moment you used it, so logically, it cannot be extended any more. A "visa" is for entering, and a "stay permit" is for staying in a country.
What you get stamped into your passport at the border, is an “admitted until” stamp, in simple words: “a stay permit”. It is NOT a “visa”
Now let’s assume that 95% of the people who answered you on Facebook, used the wrong wording as well and believe in “visa extensions” . . . . it sometimes makes you wonder if you can ever receive a thumb solid information in a Facebook Group.
It is like the roll of dice
And before I leave the discussion: Yes you can get your “visa” extended on immigration (sorry for using the wrong expression), just get up from your hocks and shuffle to the next immigration to listen to what they say