You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you today?

USER: I want to change my reservation due to health problem, can you help me?

ASSISTANT: I am sorry to know that. I will help you. Please let me know with your name.

USER: I am Katherine Nelson.

ASSISTANT: Please allow me a minute.

USER: Sure.

ASSISTANT: Thank you. Katherine Nelson, I am really sorry to inform you that there is no booking done on your name.

USER: No problem, thanks for checking.

ASSISTANT: Thank you for reaching us. Have a wonderful time.