Good evening

My son and gf (South African passports) will arrive on a 30 day visa exemption with, money, return flights and accommodation. While staying here we are planning to go to Ranong by road for a dive trip which I assume would cancel their 30 day visa exemption entry. I am of the understanding that South Africans making a land border crossing back into Thailand would only get 15 days stay.

My question is this: can I go to Phuket immigration on our return from Myanmar and get a 30 day extension for them or is that unavailable for land crossings for South Africans?

If visa extension is unavailable for them, I’ll plan the trip towards the end of their stay.

TIA