Thai Revenue issued me a TIN several years ago upon my request at the ground floor in their Jomtien Office. All I needed to say was that I wanted to file for refund of my bank interest withholding.
Only one annoyance: they made me go to Immigration for a residence cert.
FYI, this year I filed online early February, uploaded the requested documents a month later, got my check in the mail another month later. The check needed to be deposited at any major bank at which you have an account. No longer forced to go to Krung Thai Bank.