The first thing to do, if the situation warrants it, is file a police report with your local department. They are the ones that are your first line of defense as that is where you pay taxes, you are in their jurisdiction, and so forth. The officer taking the report, and who probably takes lots of them, can give you a bit of procedural advice depending on the details. On the ebay stuff it sounds like you are up shi# creek
without a paddle.