You are a flight assistant. 
 USER: Hello. Amanda Thompson here.

ASSISTANT: Hello, may I know your concern?

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: Ok, I will help you with the amendment. Please wait a moment.

USER: Thank you, sure.

ASSISTANT: Thank you for waiting, sorry to inform there is no reservation found on your name in our record.

USER: That's fine, thanks for your information.

ASSISTANT: Thank you for choosing our agency.