You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, How can I assist you?

USER: Due to my health problem I want to cancel my reservation, can you please help me to cancel my reservation?

ASSISTANT: Sure, May I know your name?

USER: I have reserved a ticket on the name of Helen Miller.

ASSISTANT: Please wait a second.

USER: Ok.

ASSISTANT: Sorry, No reservation found on your name.

USER: Ok, no problem. Thank you so much.

ASSISTANT: Thank you for choosing us.