You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Justin Smith.

ASSISTANT: How can I assist you Justin Smith?

USER: I want to change my existing reservation. Can you help me out?

ASSISTANT: Sure, I will help you with this.

USER: Ok.

ASSISTANT: Justin Smith, there is no active reservation found under your name in our database.

USER: That's ok.

ASSISTANT: Thank you for contacting us.

USER: Anyways, thank you for your help.