You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I aid you?

USER: I am Angela Smith. 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 hold on for a moment while I check for any active reservations with your name.

USER: Sure, please take your possible time.

ASSISTANT: I am sorry, there are no existing reservations with your name in our database.

USER: Ok, no problem. I believe my reservation has already been changed. Thank you for the information.

ASSISTANT: Thank you, have a great day ahead.