You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am David Collins.

ASSISTANT: How may I assist you?

USER: I am planning to cancel my recent reservation, due to health issue. Can you please cancel my ticket?

ASSISTANT: Sure, I am here to help you. please wait a moment.

USER: Thank you.

ASSISTANT: David, no reservation has been found on your name in our records.

USER: That's fine.

ASSISTANT: Thank you for choosing us.

USER: Thank you for your service.