You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you?

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

ASSISTANT: Sure, can I know your name for checking your previous reservation?

USER: Myself Mary Campbell.

ASSISTANT: Ok, wait for a second.

USER: Sure.

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

USER: No problem, thanks for checking.

ASSISTANT: Thank you for contacting us.