I am with airac above - and with CAP493's "item 3, sub-section"! The obvious step is often overlooked. Raise the point with the person concerned, in private, but fairly formally and seriously but without being aggressive. Point out your perception of events and how you feel - after all, it is always possible that you might receive an apology and part the best of friends. Bearing in mind that there are always two sides to any dispute, the other party might well feel somewhat aggrieved (regardless of what has transpired) if you go directly to more formal action without bothering to take this step.