You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I best assist you now?

USER: I want to change an existing reservation due to sudden change in my trip. Can you help me?

ASSISTANT: Sure, May I know your good name please?

USER: Andrew Nelson here.

ASSISTANT: Ok, please wait for a while.

USER: Ok.

ASSISTANT: We are sorry to say that, there is no active reservation found on your name.

USER: No issue, Thank you for the information.

ASSISTANT: Thanks for approaching us, wish you a great day.