You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I planned a trip to Seattle but because of financial issues, I want to change my reservation. Can you help me?

ASSISTANT: Ok, may I know your name please for further process?

USER: I reserved the ticket on the name Larry Williams.

ASSISTANT: Please wait for a moment.

USER: Ok.

ASSISTANT: Larry, can you please help me with your airports codes please because I found a reservation?

USER: Sure. I am departing from Boston BOS airport on 10/12.

ASSISTANT: Ok, may I know your return date and destination airport code please?

USER: My return date is on 10/14 from Las Vegas LAS airport.

ASSISTANT: Sorry Larry, there is no flight found as per your travelling details.

USER: That's ok, thank you for your information.

ASSISTANT: You are welcome.