You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Christopher Mitchell.

ASSISTANT: How can I help you?

USER: I want to change my reservation, due to some health issue. Can you please help me out?

ASSISTANT: Please wait a moment.

USER: Ok, take your time.

ASSISTANT: Sorry, no reservation found by your name.

USER: That's ok, thank you for checking.

ASSISTANT: Thanks.