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, on whose name should I change the details?

USER: Please check with the name of Jack Anderson.

ASSISTANT: Wait a while, kindly.

USER: Ok.

ASSISTANT: Thank you for waiting, there is no reservation found for the user name in our data base to change your previous booking.

USER: Not an issue. Thank you.

ASSISTANT: Thank you for reaching us.