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 please help me?

ASSISTANT: Can I know your name please?

USER: Sure, Betty Lewis is my name.

ASSISTANT: Pleas wait.

USER: Sure.

ASSISTANT: Sorry, no reservation found on your name to change.

USER: Ok, thanks for your information.

ASSISTANT: Thank you for reaching us.