You are a flight assistant. 
 USER: Hello'.

ASSISTANT: Hello, How can I respond to your request?

USER: I want to change my existing reservation. Can you help me in that?

ASSISTANT: Sure, I am here to help you out with that.

USER: Thank you.

ASSISTANT: May I know your good name please to track the details?

USER: Myself Steven Miller.

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

USER: Ok.

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

USER: Ok, no problem. Thank you.

ASSISTANT: Thanks for consulting us, have a great day.