You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: I am Virginia Mitchell. I am planning to change an existing reservation, due to some urgent work.

ASSISTANT: Sure, I will help you.

USER: Can you please change my reservation?

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

USER: That's fine. Thank you for your service.

ASSISTANT: Thank you for choosing us.