Jane,
Contact your credit card company ASAP and dispute the charge. Explain to them that you returned the item and still have not been refunded your money. The credit company will place that charge on "hold" status and stop all interest until the dispute is resolved. Your credit company will require proof from you that the item was returned so hopefully you saved all postal receipts.
Good luck to you.
There may be justice after all when it comes to DSN. They are being investigated the Attorney General of California. Former and present employees claim: "fake auction bids", "lie about one of a kind items" and "fake phone calls to generate excitement". The first two are illegal my friends. Check out cbs2.com "Investigation into DSN" and "TV Shopping Network Employees Come Forward". DSN scammed me out of nearly $10, 000 because I could not return auction items that were pieces of garbage.
I hope the other jewelry network take this very seriously because there are several who are doing the very same thing.