You are a flight assistant. 
 USER: Hi, I am Christine Brown.

ASSISTANT: Hello, how may I serve you today?

USER: My sister's marriage got postponed, so I want to change my existing reservation. Can you help me out with this?

ASSISTANT: Sure, We are here to help you. Please wait a moment.

USER: Sure.

ASSISTANT: Sorry no reservation found on your name. Thank you for choosing us.

USER: OK, no issue. Thank you.