You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you today?

USER: I want to change an existing reservation, so please help me in changing the reservation.

ASSISTANT: Sure, we are here to help you. May I know your name please to proceed further?

USER: Myself Ruth Green.

ASSISTANT: Please wait for a while.

USER: Ok.

ASSISTANT: Sorry to inform you that there is no active reservation found on your given name.

USER: Not an issue. Thank you.

ASSISTANT: Thanks for contacting us.