You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I best help you now?

USER: I want to change my existing reservation, Can you please help me to change it?

ASSISTANT: Sure, I can change your reservation right now. Before that I need to know your good name please?

USER: Thanks for accepting my request, my name is Debra Smith.

ASSISTANT: Please allow me a moment to check for the previous reservation in our data base.

USER: Sure.

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

USER: Ok, thanks for your assistance.

ASSISTANT: Thanks for approaching us.