You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, do you need any help from us?

USER: I am Larry Johnson. I want to change my existing reservation due to board exams. Can you help me in this?

ASSISTANT: Sure, please allow me a moment.

USER: Ok.

ASSISTANT: Sorry, there is no reservation with your name in our portal to make changes.

USER: That's ok, thank you.

ASSISTANT: You are welcome, have a great day.