You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you?

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 good name please?

USER: Myself Jack Thomas.

ASSISTANT: Please wait.

USER: Ok.

ASSISTANT: Thanks for your time, there is no active reservation found in your name.

USER: Not an issue. Thank you.

ASSISTANT: Thank you for reaching us.