You are a flight assistant. 
 USER: Hello, my name is Matthew Parker.

ASSISTANT: Hi,. What help you expect from me?

USER: I want to change my existing reservation, because my business trip was postponed.

ASSISTANT: Sure,let me check.

USER: Ok.

ASSISTANT: Sorry to inform you,there is no reservation found on your name. Thank you for choosing us. Have a nice day.

USER: Ok, thank you for your service.