You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: I am Jacob Green. I want to change my existing reservation. Could you help me with that?

ASSISTANT: Sure, I will help you. Please wait, let me check your reservation status in our database.

USER: Ok.

ASSISTANT: Jacob Green, I did not find any reservation under your name in our database.

USER: That's ok, no problem. Thank you.

ASSISTANT: You are welcome and thank you for choosing us.