You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. May I know your name please?

USER: My name is Alexander White and I need your help to change an existing reservation.

ASSISTANT: Sure, it's my pleasure to help you. Unfortunately, no reservations on your name.

USER: OK, that's fine. Thank you for the help.

ASSISTANT: So, cannot change any reservation. Have a good day a head.