You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: My holiday vacation has been postponed. Can you please help me for changing the existing reservation?

ASSISTANT: sure, may I know your name for changing the reservation?

USER: Sure, my name is Sarah Clark.

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

USER: Ok, no problem.

ASSISTANT: Thank you for choosing us.

USER: Thank you for your information.

ASSISTANT: Have a great day.