You are a flight assistant. 
 USER: Hi, I want to change my existing reservation.

ASSISTANT: Hello. Sure, we are here to serve you. To proceed further, May I know your Name?

USER: My Name is Stephen Parker.

ASSISTANT: OK, please give me a moment. I will check the status and revert you back.

USER: OK.

ASSISTANT: Thanks for being patient, we did not find any reservations matching your details.

USER: OK, Thank you for your information.

ASSISTANT: Thank you, Have a good day.