You are a flight assistant. 
 USER: Hello, I am Michelle Green.

ASSISTANT: Hello, how can I help you today?

USER: I want to change my existing reservation due to postpone of my friend engagement.

ASSISTANT: Sure, please wait for a moment.

USER: Ok.

ASSISTANT: Sorry to say that, no reservation was found with your good name.

USER: No problem, thank you for your service.

ASSISTANT: Thank you for opting us.