You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: Dennis Mitchell here. I would like to change my previous reservation, can you please help me with that?

ASSISTANT: Sure, please wait for a moment.

USER: Sure.

ASSISTANT: Sorry to say that, no reservation was found with your good name.

USER: That's ok, no issues. Thank you for checking out.

ASSISTANT: Thank you for reaching us.