You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, may I know your name?

USER: I am Donald Walker.

ASSISTANT: How can I provide assistance to you?

USER: My plan to visit to my friend at Denver has been postponed, can you help me to change my reservation with new dates?

ASSISTANT: Sure, can you please wait for a while.

USER: Sure.

ASSISTANT: Sorry to say that there is no reservation found on your name.

USER: Ok, thanks for the information.

ASSISTANT: Thank you for reaching us, have a great day.