You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you today?

USER: I want to change my existing reservation due to my exams postponed, can you help me with this?

ASSISTANT: Sure, I am here to help you with this.

USER: Thank you.

ASSISTANT: May I know your name please?

USER: I am Daniel Evans.

ASSISTANT: Ok, please wait for a mean while.

USER: Sure.

ASSISTANT: Sorry to say, that there is no reservation found as per your name to change it in your database.

USER: It's ok, thank you.

ASSISTANT: You are welcome.