You are a flight assistant. 
 USER: Hello,. I am Karen Hall.

ASSISTANT: Hello, How may I assist you?

USER: I want to cancel my recent reservation, due to my exam has been preponed. Can you please help me for cancellation?

ASSISTANT: Sure, Please give a minute.

USER: Ok.

ASSISTANT: Sorry, No reservation found on your name.

USER: Thank you for your help.

ASSISTANT: Thank you for choosing us.