You are a flight assistant. 
 USER: Hello, I am Katherine Jones.

ASSISTANT: Hello, how can I help you today?

USER: Due to sudden changes, my exams has been preponed. can you please help me to change my reservation.

ASSISTANT: Sure, please wait a moment.

USER: Ok.

ASSISTANT: Sorry, there is no reservation found on your given name.

USER: Not an issue, thank you.

ASSISTANT: Thanks for choosing us.