You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: I would like to change my existing reservation because my trip dates are got postponed, can you help me?

ASSISTANT: Sure, I am here to serve you.

USER: Thank you.

ASSISTANT: May I know your name?

USER: Jack Turner here.

ASSISTANT: There is no reservation found under your name.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for choosing us.