You are a flight assistant. 
 USER: Hi, I am Alexander Parker.

ASSISTANT: Hello, How could I serve you today?

USER: As I have an emergency work in my office, I have to change my existing  reservation.

ASSISTANT: Sure, I am glad to help you. Wait a moment I will check with your existing reservation and get back to you.

USER: Ok.

ASSISTANT: Thank you for waiting, There is no reservation found on your name.

USER: Ok, not a problem. Thank you for your information.

ASSISTANT: Thank you for approaching  us, Have a good day.