Hi. I'm new here. My gf and I bought the tickets to go to Hong Kong on 8/20 from travel agency, but we want to change the flight schedule to 8/13. Does anyone know if we can go to the airport on 8/13 and change the schedule? or we must change the flight schedule from travel agency? Travel agency said they will charge us $500 each, I think it's a lot .... so does anyone know any other way that we can change the schedule for less money? Thank you