Hello, myself Jason Thomas.
Hello. How may I help you today?
I want to change my destination airport code in my  existing reservation, could you please help me out?
Sure, I am here to help you to change your reservation with your new airport codes, please wait for a minute.
Ok, take your time.
Sorry Thomas, based on your request I searched with your name in our reservation database, but I could not find any previous reservation with your name.
It's ok, thank you for the information.
Welcome, thanks for choosing us.