You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you today?

USER: I want to change my reservation, because my exam have been postponed, can you help me in changing?

ASSISTANT: Sure, I will help you. Please, forward me your name to check your reservation status.

USER: My name is Donald Baker.

ASSISTANT: Ok, please wait for a while.

USER: Sure, take your time.

ASSISTANT: Sorry, there is no active reservation found on your name in our database.

USER: That's ok, thank you for your information.

ASSISTANT: Thank you for choosing us, have a good day.