You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, what can I do for you today?

USER: I am planning to change an existing reservation, due to health issue. Can you please help me out?

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: On whose name, you want to change the reservation?

USER: My name is Katherine Young.

ASSISTANT: Ok, please standby.

USER: Sure.

ASSISTANT: Sorry to say that, no reservation was found on your good name.

USER: That's fine, thank you for your service.

ASSISTANT: Thank you for choosing us.