You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hi. How  may I help you?

USER: I want to change my reservation due to heath problem, can you help me? My name is Katherine Thomas.

ASSISTANT: Sure, I will help you with that, may I know your name please? I am sorry Katherine Thomas, no reservation found as per your details.

USER: No problem.

ASSISTANT: Thank you.

USER: Thank you for your help.