You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you?

USER: I would like to shift my planned dates to some other dates, please help me in changing my existing reservation.

ASSISTANT: Sure, I can help you with that. May I know your good name please?

USER: My name is William Thompson.

ASSISTANT: Ok, please wait for a while.

USER: Sure, take your time.

ASSISTANT: William Thompson, there is no active reservation found under your name to do changes in that.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Thank you for choosing us.