You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

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

ASSISTANT: Sure, can I know your name please?

USER: Myself Debra Davis.

ASSISTANT: Please wait for some while.

USER: Ok.

ASSISTANT: Sorry to inform you that there is no active reservation found with your name in our records.

USER: Ok, not a problem. Thank you.

ASSISTANT: Most welcome.