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 please help me to change my reservation which I have done last week?

ASSISTANT: Sure, please wait for a moment to check your details. Meanwhile, may I know your name?

USER: Myself Robert Harris.

ASSISTANT: Sorry, there is no reservation found on your name. Thank you for choosing us, have a nice day.

USER: No problem, thanks for checking.