@Joonas ********
, as a rule you have to go back to the immigration office that put the stamp in your passport (SO if you were one of those people on the Island of Misfit Toys who had the mobile immigration thing come and give out under consideration stamps) LOOK at the stamp and see if it says Surat Thani or Surat Thani (Samui) because that's how they're stamped
Here's the contact info, call them and ask OR post on one of the island groups those people will know
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