You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you?

USER: Can you please help me in changing my existing reservation?

ASSISTANT: Sure, I am here to help you with that, can I know your good name to proceed further?

USER: I am Lisa Davis.

ASSISTANT: Thank you. Please be online for a while. I will check your reservation status and get back to you.

USER: Ok.

ASSISTANT: I am sorry to say you that there is no reservation found under your name in our database.

USER: Ok, no problem. Thank you.

ASSISTANT: Welcome Lisa Davis.