You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: Due to my ill health, I would like to change my existing reservation. Please help me out.

ASSISTANT: Sure, I will help you out. Please provide me your name.

USER: My name is Lisa Williams.

ASSISTANT: Please wait a moment, let me check the previous reservation on your name.

USER: Sure.

ASSISTANT: Sorry Williams, no reservation found on your name.

USER: Ok, no issue. Thank you for your information.

ASSISTANT: Thank you for reaching us.