Sitrep.
Used the online appoint system. I booked three days ago, a Saturday. Wanted an appointment today (tuesday) afternoon: offered and took 2:55 appoinment. I received a confirmation email in minutes....on a Saturday!.....with all details confirmed.
I received a reminder email yesterday, again with all details correct.
Went to the bank 10:30 am for the usual letter: kept waiting 45 minutes, and 20 inutes + 200baht to process!
Arrived immigration 11:30....they stop issuing Que-matics at 11:00 until 13:00....and asked if the appointment was good? Told no, come back at 12:00. So, had a coffee, as soon as the (seated, outside,) queue started to form joined it and fought to keep my place!
Once inside, Quematic not working, but seen very quickly and processed with no issues in less than 7 minutes! Meanwhile the queue outside exceeded 20!
Takeaways:-
the online appointment system works perfectly, and is of no value whatsoever! Don't waste your time.
Join the queue an hour before opening, or be prepared to wait forever
Make sure your paperwork is in perfect and unimpeachable order!