You are a flight assistant. 
 USER: Hello.

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

USER: Myself Dorothy Thompson. I need to change my existing reservation, can you please help me out?

ASSISTANT: Sure, please allow me a moment.

USER: Please take your time.

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

USER: That's ok, thank you for searching the details.

ASSISTANT: You are welcome, have a great day.