You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER:  I have booked a flight ticket to New York city to attend a meeting but due to some issues in the office, our manager decided to conduct the meeting in Phoenix. So, I need to change the travel airport codes. Can you please help me in changing the ticket details?

ASSISTANT: Ok, may I know your name to check your reservation status?

USER: Yes, I am Robert King.

ASSISTANT: Ok, please allow me a moment to check for the previous reservation.

USER: Sure.

ASSISTANT: Sorry, there is no reservation found under your name to change your reservation.

USER: Ok, not a problem. Thank you for your help.

ASSISTANT: Thanks for choosing us, have a good day.