You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I aid you?

USER: I am Kathleen Allen. 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.

USER: Sure.

ASSISTANT: Sorry, there is no reservation found on your name in our database to change.

USER: No issues, thank you for your help.

ASSISTANT: You are most welcome.