You are a flight assistant. 
 USER: Hello, I am Jeffery Miller.

ASSISTANT: Hello, how can I help you?

USER: Due to some entrepreneurship meeting, I am going to change my existing reservation. Can you please help me in changing the reservation?

ASSISTANT: Sure, I'm gleeful to help you in changing your reservation.

USER: Thank you.

ASSISTANT: Please wait for a while let me check for the previous reservation.

USER: Sure, take your time.

ASSISTANT: Thank you for waiting.

USER: Ok.

ASSISTANT: Sorry Miller, no reservation found under your name in our database to modify it.

USER: No problem, thanks for your information.

ASSISTANT: Thank you for reaching us.