You are a flight assistant. 
 USER: Hello, my name is Christopher Edwards.

ASSISTANT: Hello, how can I help you today?

USER: I want to change my existing reservation due to postpone of my meeting.

ASSISTANT: Ok, please wait for a minute, let me check and get back to you.

USER: Ok.

ASSISTANT: Thank you for waiting. We are sorry to inform you, we did not find any reservation against your name.

USER: Ok, thanks for your service.

ASSISTANT: Thank you for choosing us. Have a nice day.