You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you?

USER: I ma Michelle Martin.

ASSISTANT: Ok.

USER: Will you please change my existing reservation?

ASSISTANT: Sure, please wait for a moment.

USER: Sure.

ASSISTANT: Sorry, no reservation found with your name.

USER: Ok. Thank you.

ASSISTANT: Thank you for opting us.