I learnt this travel agent via 泰友營 2 years ago. I booked Chiang Mai package for 13 people. It's also my fault that I didn't check the e-tickets carefully - only when we arrived BKK airport, then I was told the 13 people were booked on 2 returning flights and the kids were not on the same plane as their parents. I called the agent and he said the airline was closed on Sat, he could check it out on Monday. He didn't apologize for making a mistake and I was very angry.
I waited for 2 nights and on Monday, we were all confirmed on the same flight.