You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, How can I assist you?

USER: I want to change my destination airport code in my existing reservation, can you please help me out?

ASSISTANT: Sure, May I know your name?

USER: Sure, my name is David Smith.

ASSISTANT: Please wait a moment.

USER: Ok, take your time.

ASSISTANT: Sorry, No reservation found on your name.

USER: It's ok, thank you for the information.

ASSISTANT: Thank you for availing us.