Legal Question in Civil Litigation in California

If you don't have proof, that is the end of any easy resolution. Theoretically, you could sue, seek a subpoena of their physical record books, and try to find an entry in their books showing your consignment order. I find it hard to believe there is no such record kept, or that they rely entirely upon your receipt stub. If that is all it took, how would the store be able to prevent someone from 'creating' a fraudulent receipt and presenting it as 'proof' in a lawsuit.