You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am David Green.

ASSISTANT: How may I assist you today?

USER: I need to cancel my reservation as my meeting got postponed, can you please help me out?

ASSISTANT: Please give me a moment.

USER: Ok.

ASSISTANT: There is no reservation found with your given name in our data.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for choosing us.