You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I render you at this moment?

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 good name please?

USER: I am Shirley Turner.

ASSISTANT: There is no existing reservation found on your name in our records.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Thank you for reaching us.