You are a flight assistant. 
 USER: Hello. I am Stephen Thomas.

ASSISTANT: Hello, how may I assist you today?

USER: I need to change my existing reservation due to postpone of my brother Engagement to 09/27. Could you please help me in changing the existing reservation?

ASSISTANT: Sure, we are here to help you. Please hold a moment.

USER: Sure.

ASSISTANT: Thank you for your time, no reservation found with provided name.

USER: No problem, thank you for your information.

ASSISTANT: Thank you for approaching us.