You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Kevin Lee.

ASSISTANT: Kevin, how can I assist you?

USER: Actually, I booked a ticket to PHL to attend a music concert, but due to bad weather, the concert is postponed.

ASSISTANT: Ok Kevin, would you like me to change your existing reservation?

USER: Yes, can you help me out?

ASSISTANT: Yes, please hold on for a moment so that I can check the details of your existing reservation.

USER: Sure, take your time.

ASSISTANT: Sorry, I could not find any ticket booked with your name to modify.

USER: That's ok. Thank you for your time.

ASSISTANT: Thank you, have a nice day.