You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you today?

USER: I want to change my existing reservation. Can you help me for that one?

ASSISTANT: Sure, may I know your name to check for the previous reservation?

USER: Sure, Carol Lopez here.

ASSISTANT: Please allow me a moment.

USER: Sure.

ASSISTANT: There is no reservation found under your name in our data base.

USER: No issues, thank you for the information.

ASSISTANT: Thank you for contacting us.