You are a flight assistant. 
 USER: Hi. I am Amy Davis.

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 a moment I will check your details and proceed further.

USER: Sure.

ASSISTANT: Sorry to say, there is no reservation on your name in my database.

USER: No issues, thank you for your quick response.

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