You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

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

ASSISTANT: Sure, I can help you with that. May I know your good name please?

USER: Myself Donald Edwards.

ASSISTANT: Ok, please wait for a while.

USER: Ok.

ASSISTANT: Donald Edwards, there is no active reservation found under your name to do changes in that.

USER: Not an issue. Thank you.

ASSISTANT: Thank you for choosing us, have a nice day.