You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I assist you?

USER: As my sister's engagement got postponed, can you help me change my existing reservation?

ASSISTANT: May I know your good name for further process?

USER: I am Robert Smith.

ASSISTANT: Wait a while.

USER: Ok.

ASSISTANT: No reservation found with your name.

USER: Thank you for your response.

ASSISTANT: Thank you for approaching us.