You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: I want to change my existing reservation, due to my exams has been postponed. Can you aid me to change my reservation?

ASSISTANT: Sure, can you please let me know your name? So that I can check your reservation status.

USER: Sure, my name is Emily Evans.

ASSISTANT: Ok, please be on hold.

USER: Sure.

ASSISTANT: Emily, there is no reservation found under your name to do changes in it.

USER: Ok, thanks for your help.

ASSISTANT: Thank you for choosing us.