You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you?

USER: I would like to change my flight reservation as I am sick, could you please help me?

ASSISTANT: Sure, I am here to help you out.

USER: Thank you.

ASSISTANT: May I know your name please?

USER: I am Mark Davis.

ASSISTANT: Mark Davis, we haven't found any reservation under your name in our database with your preferences.

USER: No problem, thank you for checking.

ASSISTANT: Thank you for choosing us.