You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you?

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

ASSISTANT: Yes, I can help you.

USER: Thank you.

ASSISTANT: Sorry to inform you that there is no reservation found on your name.

USER: Ok, no problem.

ASSISTANT: Thank you for reaching us.

USER: Thanks for your information.