You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid 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.

USER: Thank you.

ASSISTANT: May I know on whose name the ticket has been reserved formerly?

USER: My name is Michelle Martinez.

ASSISTANT: Ok, hold on for a moment. Let me check.

USER: Ok, take your time.

ASSISTANT: Sorry Michelle, there are no flights reserved on your name formerly.

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

ASSISTANT: Welcome, thank you for choosing us. Have a great day.