You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I serve you today?

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

ASSISTANT: Sure, I am here to help you with this. May I know your good name please?

USER: Thanks. My name is Karen Hall.

ASSISTANT: Ok, wait for a mean while please.

USER: Ok, take your time.

ASSISTANT: Sorry Hall, there is no flight found as per your travelling details.

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

ASSISTANT: You are welcome.