You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, what kind of service you are expecting from us?

USER: I am Jeffrey Miller, I want to change my reservation. Can you help me?

ASSISTANT: Sure, I can help you to change your reservation.

USER: Thank you.

ASSISTANT: Please wait, I will find your reservation and change it as per your request.

USER: Sure.

ASSISTANT: Thanks for waiting. I regret that there is no reservation found on your name to change.

USER: Ok, thank you for informing me.

ASSISTANT: Thanks for approaching us, hope to serve you again.