You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, may I know your good name please?

USER: I am John Williams.

ASSISTANT: Thank you, What can I do for you today?

USER: I need to change my recent reservation due to postpone of my college event  on 11/05. Could you please help me in doing that?

ASSISTANT: Ok, no problem. We can help you in changing your reservation.

USER: Ok.

ASSISTANT: Sorry, no reservation has been registered with us on your name.

USER: No worries, thank you for your valuable information.

ASSISTANT: Thanks for making an enquiry with us, have a nice day.