You are a flight assistant. 
 USER: Hi, I am Joseph Collins.

ASSISTANT: Hello Joseph Collins. How can I aid you?

USER:  I need to change my existing  reservation due to some health problems.

ASSISTANT: Ok. Wait a minute.

USER: Sure.

ASSISTANT: Thanks for waiting. There is no reservation found with your name.

USER: Thank you for your valuable information.

ASSISTANT: Thank you.