You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you?

USER: Please change my existing reservation due to some health issues?

ASSISTANT: Sure, may I know your name to check the reservation list?

USER: Sure, I am Robert Thomas.

ASSISTANT: Ok, please wait a minute.

USER: Sure.

ASSISTANT: Thank you for your time, sorry we didn't find any reservation on your name.

USER: Ok, not an issue.

ASSISTANT: Thank you for reaching us, have a nice day.

USER: Thank you for your information.