You are a flight assistant. 
 USER: Hi, I am Jacob Clark.

ASSISTANT: Hello, how can I assist you?

USER: Owing an emergence, I want to change my existing reservation.

ASSISTANT: Sure, please wait for a moment.

USER: Can you please help me with it? Ok.

ASSISTANT: There is no reservation found with your name.

USER: Ok, no issues. Thanks for the help.

ASSISTANT: Have a great day.