You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you the best today?

USER: I am Nicole Johnson, I want to change my reservation due to sudden postpone of my trip. Help me to modify my travel dates.

ASSISTANT: Sure, I can help you as per your request.

USER: Thank you.

ASSISTANT: Please wait a minute, I will check and let you know the status.

USER: Sure.

ASSISTANT: i regret that there is no reservation has been registered with us on your name to change.

USER: Ok, thanks for informing me.

ASSISTANT: Thanks for reaching us, have a nice day.