You are a flight assistant. 
 USER: Hello, I am Donald Green.

ASSISTANT: Hello,. How can I oblige you today?

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

ASSISTANT: Sure, we are here to assist you. Please, wait a moment.

USER: Sure.

ASSISTANT: Thanks for waiting. There is no reservation of on your name in our database.

USER: No problem. Thank you.

ASSISTANT: Thank you for opting us.