You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you?

USER: Due to some office meeting, I am willing to change my reservation. Can you please help me for this?

ASSISTANT: Sure, I am glad to help you. May I know your name?

USER: Myself Alexander Lee.

ASSISTANT: Please provide your airport codes.

USER: My new airport codes are SEA to DFW?

ASSISTANT: May I know your travel dates?

USER: I am planning my trip on Aug 19 and again I will be return back on Aug 21.

ASSISTANT: Do you have any specifications?

USER: I am flexible to travel in direct flight.

ASSISTANT: Please wait for a while.

USER: Sure, I will wait for your response.

ASSISTANT: Sorry Alexander Lee, no direct flight is available on your route.

USER: Not a big deal, anyhow thank you very much for your service.

ASSISTANT: Thank you for reaching us.

USER: You are welcome.