You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you?

USER: I am Charles Hall, I want to change my existing reservation due to my health issue.

ASSISTANT: Sure, give me a minute.

USER: Ok, sure take your time.

ASSISTANT: Sorry, there is no reservation found under your name.

USER: It's ok, anyway thank you for the information.

ASSISTANT: Thank you for reaching us.