You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I want to change my existing reservation, can you please help me with this?

ASSISTANT: Sure, I am here to help you. May I know your name?

USER: I am Mary Moore.

ASSISTANT: There is no reservation found under your name.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Thank you opting us.