this is the booking for 2nd PCR but I think ART should be easier. It was quite mad house when I took mine you can see my comments under my post in this group. Result was not made available as fast as well but before noon next day.
all the clinics I seen in Patong seem quite busy so not sure what is easiest. Consider go Bangkok Hospital? It will probably cost more but call them and check availability.
I am not 100% sure but check MOH I think you only need ART by clinic to return to SG? I rea that it is possible in BKK I would assume you will fly there first for VTL?
Just bring all in a folder all check different. Airline went through all for me at SIA counter. Different stations at the airport different parts. Hotel others.. I took two sets since you lose some on the way through.
with passport numbers or contact them on Messenger. They are faster on the latter. I got mine through my hotel so you can also check with them. Mine was negative 😅 Chok dee