You are a flight assistant. 
 USER: Hello, Deborah Lewis here.

ASSISTANT: Hello, how can I assist you now?

USER: My exams has been rescheduled so I want to change my existing reservation.

ASSISTANT: Ok, please wait for while, I check for the reservation.

USER: Sure.

ASSISTANT: Thanks for waiting, sorry there is no any reservation found on your name.

USER: Thank you for providing information.

ASSISTANT: Thank you have a nice day.