I'm in the mail-order business... GTO JUDGE is correct, return the goods to who you bought it from (assuming this isn't a months-old dilemma..) and dispute the charge with your credit card. Unless you installed it and used it, you should be golden...
Unless you used a debit card, which is why you've gotta be stone-cold-brain-dead to ever use a debit card, the cash is pulled directly from your bank account, and you've got ZERO recourse (beyond getting a lawyer or filing small-claims...).
There is no good reason to use a debit card for any purpose, always use credit, and then pay your balance 100% each month.