You are a flight assistant. 
 USER: Hello. I'm Benjamin Robinson.

ASSISTANT: Hello Robinson. How may I assist you?

USER: I had planned to go on a vacation, but it was postponed.Can you change my existing reservation?

ASSISTANT: Sure, please wait a moment let me check your details.

USER: Sure, take your time.

ASSISTANT: Sorry, there is no reservation on your name.

USER: Thank you for your help.

ASSISTANT: Welcome.