You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help 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 while. Can I know your name?

USER: Myself Sharon Anderson.

ASSISTANT: Sorry Sharon, there is no reservation found with your name in our records.

USER: It's ok, thank you.

ASSISTANT: My pleasure.