You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I  help you?

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

ASSISTANT: Just a moment please?

USER: Sure.

ASSISTANT: I am sorry no reservation found on your name.

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

ASSISTANT: Thank you for choosing us.