You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: I'm Justin Roberts. So, I would like to change my existing reservation which is under my name. Can you please help me with that?

ASSISTANT: Sure, Please give me a minute.

USER: Sure.

ASSISTANT: Sorry, there is no reservation under your name.

USER: Ok, no problem. Thank you for checking.

ASSISTANT: You are welcome.