You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I aid you?

USER: I am Patrick Lee, I want to change my reservation which I have done last week.

ASSISTANT: Sure, please wait a moment I will check your details and proceed further.

USER: Thank you.

ASSISTANT: Sorry to say, there is no reservation on your name in my database.

USER: It's ok, anyway thank you for the help.

ASSISTANT: Thank you for reaching us, have a nice day.

USER: Most welcome.