You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I serve you now?

USER: I want to change my existing reservation due to sudden postpone of my trip dates. Can you help me with that?

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: May I know your good name please?

USER: I am Ryan Scott.

ASSISTANT: Please wait for a moment.

USER: Sure.

ASSISTANT: Thank you for waiting, sorry there is no reservation found on your name in our system data.

USER: Ok, no issues. Thank you.

ASSISTANT: Thank you for visiting us.