You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you?

USER: Could you please change my existing reservation due to postpone of my trip?

ASSISTANT: Sure, may I know your name?

USER: My name is George Mitchell.

ASSISTANT: Please wait a moment.

USER: Sure.

ASSISTANT: Sorry, no reservation found on your name.

USER: Not a problem, thank you for checking.

ASSISTANT: Thank you for opting us.