You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you today?

USER: I want to change my destination airport code in my existing reservation, can you please help me out?

ASSISTANT: Sure, I can change your reservation right now. Before that I need to know your good name please?

USER: Sure, my name is Nicholas Harris.

ASSISTANT: Please wait a minute.

USER: Ok, take your time.

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

USER: It's ok, thank you for the information.

ASSISTANT: Thank you for choosing us.