You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Jack Perez.

ASSISTANT: Jack, how can I assist you?

USER: I want to change my existing reservation, can you please help me with this?

ASSISTANT: Sure, let me check your reservation status. Jack, I have not found any reservation under your name.

USER: Sure. Ok, no problem. Thank you for your time.

ASSISTANT: You are most welcome.