You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Jessica Garcia here.

ASSISTANT: How may I aid you today?

USER: Due to some reason, my concert is postponed. Can you change my reservation?

ASSISTANT: Sure, I will help you with that.

USER: Thanks.

ASSISTANT: Please wait for a minute.

USER: Sure.

ASSISTANT: I am sorry to say there is no reservation.

USER: That's fine. Thank you for checking.

ASSISTANT: Thank you for contacting us.