You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello. How may I help you?

USER: Can you please help me in changing my existing reservation, as my exam got postponed.

ASSISTANT: Yes, can you share me your name?

USER: Myself, Dennis Young.

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

USER: Ok, no issues. Thank you for your help.

ASSISTANT: Thank you for contacting us.