You hop on the phone with the bank and initiate a dispute. They give the merchant a chance to prove that you specifically did indeed make the purchase and/or receive a hard product. If they can't, the money is refunded to your account.

Of course, if you keep on charging back, eventually your bank will give you a polite call to let you know that they're closing out your account. This provides the incentive to be relatively honest about charge backs in addition to the fact that a false charge back is a criminal offense (fraud).