You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you?

USER: I want to change my existing reservation due to some health issues, can you help me with that?

ASSISTANT: Sure, I am ready to help you.

USER: Thank you.

ASSISTANT: May I know your name please?

USER: Jack Lee.

ASSISTANT: Sorry, there are no reservation found on your name.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for reaching us.