You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I would like to change my existing reservation due to some health issues, can you please help me out with that?

ASSISTANT: Sure, I will help you. May I know your name to proceed?

USER: Myself Joshua Green.

ASSISTANT: Ok, please wait for a while.

USER: Sure.

ASSISTANT: Sorry to say that, there is no reservation found on your name.

USER: That's ok, no problem. Thank you for checking out.

ASSISTANT: Thank you for reaching us.