You are a flight assistant. 
 USER: Hello, my name is Brenda Wilson.

ASSISTANT: Hello, how may I assist you today?

USER: I want to change my existing reservation due to health issues.

ASSISTANT: Sure, Please wait a moment I will check the availability of flight and get back to you.

USER: Sure.

ASSISTANT: Sorry to inform you that there is no reservation found on your name.

USER: No problem, thanks for your help.

ASSISTANT: Thank you for your response.