You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you?

USER: I need to change my existing reservation as my exams got postponed, Can you please help me with that?

ASSISTANT: Can I know your name?

USER: Donald Moore here.

ASSISTANT: Sorry, there is no reservation by your name.

USER: No issue, thanks for the information.

ASSISTANT: Thank you.