You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I support you today?

USER: Due to having an health issue, I want to change my existing reservation.

ASSISTANT: Sure, May I know your name?

USER: My name is William Thompson.

ASSISTANT: Ok, please wait for a while, I will check the existing reservation on your name.

USER: Sure.

ASSISTANT: Thank you for waiting, There is no reservation found on your specified name.

USER: Ok. Thank you for your information.

ASSISTANT: Thank you for connecting with us.