You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how may I help you at this moment?

USER: Please change my existing reservation owing to an emergency.

ASSISTANT: Ok, I can help you. Please provide your name to change your reservation?

USER: I am Jonathan Clark.

ASSISTANT: Soory, no reservation has been found with your name. Thanks for approaching us.

USER: Thanks for your help.