Purely as an FYI...
Visit to the still-new Immigration Officein Mae Nam on Samui today... Wow. As painless as any government interaction I have ever had in Thailand. In and out in 20 minutes. Air con. Smoking area right nearby. Comptent and nominally helpful staff. It might almost be worth it to come here and make it a day trip from BKK, considering the hellish experiences I and other members have had there... And my overstay and full-up passport? Handled discreetly and perfectly.
TLDR : Answer Summary
A recent visitor shared a positive experience at the Mae Nam Immigration Office in Samui, noting the efficiency of the process which took only 20 minutes. Comments from others suggested that during low season, the office operates smoothly, which contrasts with longer wait times during high season. The discussion touched on the type of visas handled, including 30-day tourist extensions, and the limitations on which immigration offices can be used depending on visa status.