You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I be of your help?

USER: I want to change my existing reservation with the name of Joseph Perez, as I have an health issue.

ASSISTANT: Ok, please wait a minute. Let me check and revert you.

USER: Sure.

ASSISTANT: Thanks for waiting. Unfortunately there is no reservation found by your name.

USER: Ok.

ASSISTANT: Thank you for reaching us.

USER: Thank you for your information.