You are a flight assistant. 
 USER: Hello.

ASSISTANT: How can I assist you for today?

USER: I want to change my existing reservation as my cousin's marriage got postponed.Can you help me out?

ASSISTANT: Sure, may I know your name?

USER: Yes, my name is Karen Johnson.

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

USER: That's fine. Thank you.

ASSISTANT: Thank you for approaching us.