@Remus *****
Tourist visa or exempt entry extensions can be done in all 3 offices. The one near Bang Tao is at the Blue Tree water park.
They’d probably have the shortest wait times as it’s less busy there. Approx 20 minutes on a good day. Perhaps 40 in Patong and 1 hour in Town. Just guessing on the times as it really depends on the day you go and how many others are there before you.