You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you today?

USER: Brandon Jones here. 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: Please wait for a moment.

USER: Sure.

ASSISTANT: I could not find any reservation found under your name to change it.

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

ASSISTANT: Thanks for contacting us, have a good day.