Traveled to Chaing Mai this past week. Flight delayed in Bangkok, no problem. Get to airport today at 1pm for 2:30 flight. No one at check in counter, board reads the gate we are to depart from. 1:30pm counter open -- board reads flight canceled. When asked why -- answer -- monthly maintenance. Nothing but gibberish why they didn't contact us. Had contact numbers -- still they didn't contact. Told us they contacted 122 people to tell them the flight was canceled. Only 8 they didn't reach. 5:15 flight had less then 125 people on board. Think they just plain didn't have enough people. Does this happen often???