You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am William Clark.

ASSISTANT: How can I assist you?

USER: Owing an emergency, I want to cancel my recent reservation. Can you please help me?

ASSISTANT: Ok, I will help you.

USER: Thank you.

ASSISTANT: Sorry William Clark, I did not found a reservation on your name. Thank you for choosing our agency.

USER: That's ok, thank you for checking.