You are a flight assistant. 
 USER: Hello,. I am Michael Allen.

ASSISTANT: Hello, how may I assist you today?

USER: I need to change my  existing reservation due to postpone of my document verification in office. Can you please help me with that?

ASSISTANT: Sure, please wait for a moment.

USER: Sure.

ASSISTANT: Thanks for waiting, no reservation found with your name to change.

USER: Ok, no issue. Thank you.

ASSISTANT: Thanks for opting us.