You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you today?

USER: My name is Patrick Allen. I want to do some changes in my existing reservation. Can you help me for that?

ASSISTANT: Sure, I am here to help you. Please wait for a while.

USER: Thank you.

ASSISTANT: There is no reservation found on your name in our database.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for choosing us.