You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, do you need any help from us?

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

ASSISTANT: Ok, could I have your name please?

USER: My name is Raymond Johnson.

ASSISTANT: Ok, please allow me a moment.

USER: Ok, take your time.

ASSISTANT: Sorry, there is no reservation with your name in our portal to make changes further.

USER: That's ok, thank you for checking.

ASSISTANT: You are welcome, have a great day.