You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: Unfortunately, I want to change my existing reservation due to some problems, can you please help me out?

ASSISTANT: Sure, can you help me with your name to proceed?

USER: Sure, my name is Michelle Lopez.

ASSISTANT: Sorry, no reservation found on your name.

USER: That's fine, anyways thank you for your information.

ASSISTANT: Thank you for choosing us, have a nice day.