You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am John Anderson. Can you please change my destination code in my existing reservation?

ASSISTANT: Sure, I will help you. Please wait for a while.

USER: Ok.

ASSISTANT: Thank you for waiting. Sorry, there is no reservation found on your name in our data base to change.

USER: It's ok. Thank you.

ASSISTANT: You are welcome. Have a good day.