You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you today?

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

ASSISTANT: Sure, can you share your good name please?

USER: Angela Wilson here.

ASSISTANT: Please wait a minute.

USER: Sure.

ASSISTANT: Sorry, there is no active reservation on your name in our portal to change.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for reaching us.