You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I support you?

USER: I would like to change my existing reservation which was made on the name of Carol Roberts. Can you help me with it?

ASSISTANT: Sure, let me check the reservation list and get back to you.

USER: Sure.

ASSISTANT: We could not find any reservation in our data base with your name.

USER: That's fine. Thank you for the response.

ASSISTANT: Thank you for reaching us.