You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist 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 will help you.

USER: Thank you.

ASSISTANT: May I know your name to check the reservation data list?

USER: My name is Dennis Johnson.

ASSISTANT: Sorry Dennis Johnson, there is no active reservation on your name.

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

ASSISTANT: Thank you for choosing us.