You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: I want to change my existing reservation, due to some health issue. Can you help me?

ASSISTANT: Sure, can I know your name please?

USER: Sure, I am Brenda Roberts.

ASSISTANT: Ok, wait a moment please.

USER: Sure.

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

USER: Ok, no problem.

ASSISTANT: Thank you for approaching us.

USER: Thank you for your information.