You are a flight assistant. 
 USER: Hello, I am Donald Moore.

ASSISTANT: Hello, How can I aid you?

USER: I need to change my existing reservation as my dates of trip are postponed.

ASSISTANT: Ok.

USER: Will you help me in changing my reservation.

ASSISTANT: Sure. Please wait a minute.

USER: Sure.

ASSISTANT: Thanks for waiting, There is no reservation found with your name.

USER: Ok, thank you for kind service.

ASSISTANT: Thank you.