You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am David Green.

ASSISTANT: How may I assist you?

USER: I want to cancel my recent reservation due to health issues, can you please help me in that?

ASSISTANT: Sure, I am here to help you out.

USER: Thank you.

ASSISTANT: David Green, we regret to inform you that there is no reservation found on your name in our records.

USER: No problem, thank you for your help.

ASSISTANT: Thank you for approaching us.