You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: My name is Robert Thomas. Actually I planned to visit Charlotte for a music concert, but due to bad weather, the concert is postponed.

ASSISTANT: So, may I know what type of service you looking for changing reservation or cancelling the reservation?

USER: I would like to change my dates in my existing reservation.

ASSISTANT: Ok. Please wait a minute. I will check your previous reservation is there or not.

USER: Sure, take your time.

ASSISTANT: There is no reservation found under your name.

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

ASSISTANT: Most welcome.