You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER:  I am Jessica Hill want to change my reservation due to prepone of my exams.

ASSISTANT: Ok.

USER:  Can you help me in changing?

ASSISTANT: Sure, I am here to assist you. Please wait for a while.

USER: Ok.

ASSISTANT: Thanks for your time, there is no active reservation made in your name to change.

USER: Ok, thank you for your response.

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