You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I want to change my existing reservation due to sudden postpone of my exams.

ASSISTANT: Sure, can I know your name?

USER: Charles Jones here.

ASSISTANT: Ok, please hold on a moment.

USER: Sure.

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

USER: Ok, no issues. Thank you for your quick response.

ASSISTANT: Thank you for choosing us.