You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: I am Donald Thompson here. I want to change my existing reservation, as my exams got postponed to next month. Can you please help me in changing my existing reservation?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: Please wait a moment, I will check the status of your reservation.

USER: Ok, sure. Take your own time.

ASSISTANT: Donald Thompson, no reservation has been found on your name in our database.

USER: Ok, not a problem. Thanks for the information.

ASSISTANT: Thank you for approaching us.