Hi,
I am on TR Visa.
Entry stamp : 13 dec 2020
Went to Samut Prakan immigation on january 22th to get extension (put on the paper want 60 days extension).
I paid 1,900 THB.
My application was under consideration and I had to back on february 10th (today).
Got 60 days extenstion - Stamp until 11 april 2021
TLDR : Answer Summary
The user successfully extended their TR Visa for 60 days by visiting Samut Prakan immigration, where they submitted an application and paid a fee of 1,900 THB. They received a stamp extending their visa until April 11, 2021. A commenter inquired about the specific documents submitted for the extension.