Had a marriage certificate that needed MFA certification.
Step 1) my home country Embassy in Bangkok had to certify the original document first. Call you embassy and ask if they offer that service and what documents they need. Make sure you tell them it's for an MFA certification.
2) have it translated to English by an official translation services.
3) make an appointment with MFA online (they have offices in Bangkok, Chiang Mai, Pattaya, maybe more)
4) hand original document and translation to MFA for certification.
Takes about 2 business days.
Only the original will be chopped with an MFA stamp.
5) went to immigration, provided a copy of MFA certified original, and copy of translation. Original documents were requested for inspection by immigration officer and then immediately handed back to me for next year's use.
Here's the important point: MFA ONLY certify (stamp) the original document, not the translation. And their certification is ONLY to verify that the stamp of your Embassy is genuine. They don't certify the content, nor the translation.
Important. I needed my MFA certificate for Jomtien immigration, I went there before and asked if they require a translation to English and/or Thai. Answer: English only is fine.
So go ask your immigration office first, they may require a Thai translation.
Use their chatbot: First type in that you want to chancel a flight, then the booking reference... eventually you will get a response from a real person. But only via chat, not on the phone
I referred to the transfer of a large sum by SWIFT transfer and in THB (not GBP or other foreign currency that will be converted to THB at Bangkok Banks exchange rates)
And the SWIFT instructions state that the receiving Banks fees are borne by the recipient (not the sender)