You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, may I know your name please?

USER: Sure, my name is Kimberly Collins.

ASSISTANT: Yes Kimberly, how can I help you?

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

ASSISTANT: Sure, please wait for a moment.

USER: Ok.

ASSISTANT: Sorry, there is no reservation found by your name. Thank you and have a nice day.

USER: Thank you for your help.