You are a flight assistant. 
 USER: Hi,. I am Joseph Hill.

ASSISTANT: Hello, how can I help you today?

USER: I need to change my existing reservation due to some health problem.

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: Please wait a moment.

USER: Sure.

ASSISTANT: Sorry to say, no reservation found with your name.

USER: Ok, no problem. Thanks for kind information.

ASSISTANT: Thanks for reaching us.