You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you?

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

ASSISTANT: Sure, may I know your name?

USER: I am Ronald Taylor.

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

USER: No problem, thanks for checking.

ASSISTANT: Thank you for choosing us.