Search for and follow British reds advice on another thread;
Don't write the money off. If you ordered over the internet by credit card, simply phone your card company and tell them the goods have not been delivered and request a refund - they will reclaim the money from the vendor.
In the event you paid by some other means and can prove the transaction, call trading standards. If they can't help, take them to court in your local small claims court - it won't cost you a penny, you don't need a solicitor and you can get a court order against them. Then send in the bailifs (at their expense).
Don't get mad - get even