You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am planning to change an existing reservation, due to health issue. Can you please help me out?

ASSISTANT: Sure, may I know your name to proceed?

USER: I am Barbara Lopez.

ASSISTANT: Please wait for a moment to check your details.

USER: Sure.

ASSISTANT: Sorry, no reservation found on your name in my database.

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

ASSISTANT: Thank you for reaching us.