You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Alexander Davis, here.

ASSISTANT: How can I help you?

USER: I would like to change my reservation due to sudden change in trip plan.

ASSISTANT: Ok, give me a moment.

USER: Sure.

ASSISTANT: Sorry to say that there is no reservation found on your name.

USER: That's fine, thanks for helping me out.

ASSISTANT: You are welcome.