You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I guide you today?

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

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: Can I know your name to check your previous reservation?

USER: Sure, my name is Charles Thomas.

ASSISTANT: Please be on hold.

USER: Ok, take your time.

ASSISTANT: There is no reservation available on your name in our reservation list.

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

ASSISTANT: Thank you for reaching us, hope you have a great day.