theft

I need to share this ,my rings was sold to cash converters Nelspruit ,how can the state on there documents the person that is selling the staff is the legal owner of the goods, why are they not asking for proof of ownership. On there documents is states that the person is the legal owner weather on not they cant give the proof.we did open an case and we had to pay the double the amount that is where sold for. The rings where valuable to us .this is common theft from the buyer and the seller .how can we trust a business like cash converters. There documents that they let the customer sign without checking ownership is not executable.no everybody can sell stollen good