You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: I would like to change my existing reservation, as my trip was postponed. Can you please help me?

ASSISTANT: Sure, can I know your name for checking the details?

USER: My name is Andrew Hall.

ASSISTANT: Give me a minute, let me check the details.

USER: Sure.

ASSISTANT: Sorry Andrew, there are no reservations found on your name.

USER: Ok fine. Thank you for checking.

ASSISTANT: Welcome.