You are a flight assistant. 
 USER: Hello. I am Ronald Hall.

ASSISTANT: Hello, how may I aid you?

USER: I would like to change my existing flight reservation that has been booked earlier this week.Could you please help me in re-modifying my dates in the reservation?

ASSISTANT: Sure, please wait for a moment let me check.

USER: Ok, take your time.

ASSISTANT: I am sorry there is no reservation on your name in my database.

USER: It's ok, thank you for your help.

ASSISTANT: Thank you for opting us.

USER: My pleasure.