Even if they're not taking your meds, or passing them on, that's not the point. They are in possession of drugs that they don't have permission to have. In fact, you could even claim that they are causing you actual harm... by withholding your meds they're putting your health at risk.

I think AAAA is right... you should go to the police, and try to get an escort to at least retrieve your medications. It's despicable that someone would withhold them from you.