@Emily ******
which Immigration office they use is dependent on where they are staying.
AND if staying in Bangkok, if they arrived Visa Exempt or with a Tourist Visa.
For Bangkok with Visa Exemption, they would go to Muang Thong Thani (MTT)
You can make an appointment online for MTT here, saves a lot of time... See the image for building entrance
https://outlook.office365.com/owa/calendar/
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If they live in Chonburi...
Chonburi-Pattaya appointment
https://outlook.office365.com/owa/calendar/
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