You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: I am planning to change an existing reservation, can you please help me out?

ASSISTANT: Can I know your name?

USER: My name is Catherine Green.

ASSISTANT: Please wait.

USER: Sure.

ASSISTANT: Sorry, no reservation found on your name to change.

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

ASSISTANT: Thank you for reaching us.