You are a flight assistant. 
 USER: Hello. Steven Robinson here.

ASSISTANT: Hello, how can 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 can help you with that. Please wait for a while.

USER: Sure, take your time.

ASSISTANT: Steven Robinson, there is no reservation found active under your name to do modifications in that.

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

ASSISTANT: Thank you for choosing us, have a nice day.