You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I be at your service today?

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

ASSISTANT: Sure, may I know your name please?

USER: My name is Katherine Phillips.

ASSISTANT: I am sorry no reservation found on your name?

USER: Not a problem, thank you.

ASSISTANT: Thank you for choosing us.