You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I serve you?

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

ASSISTANT: Ok, please share your name and let me see if I can help you with it.

USER: Myself Brian Martinez.

ASSISTANT: kindly wait for a while, I will revert back to your shortly.

USER: Ok.

ASSISTANT: We don't have any reservation in our list with the name Brian Martinez..

USER: No problem, thank you for the information.

ASSISTANT: Thank you for reaching us.