How about contact the police local to that warehouse where your item is and have them accompany you to that guy and demand your item. If they deny having it they have a problem, assuming they actual did receive it. If they admit having it and can't produce some contract that allows them to hold the item ransom they have another problem. A phone call from some investigator at the PD might get this released ASAP.

That local shippers' problem is not with you and he has no right to hold this. His only recourse is against those he contracted with, assuming he has a good contract.