You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you today?

USER: I want to do some changes in my existing reservation, can you help me for that?

ASSISTANT: Sure, may I know your name?

USER: My name is Jonathan Martin.

ASSISTANT: Sorry, there is no active reservation on your name.

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

ASSISTANT: Thank you for choosing us.