If the charge was improper--i.e. you did not in fact buy that item--and the retailer will not voluntarily refund the money, you could sue (including potentially in small claims court) to recover the money. If you actually did buy the item, want a refund, but the retailer has a no refund (at least, no refund under theses circumstances) policy, you cannot get your money back--the law does not requirer retailers to allow refunds; but if the retailer does have a refund policy and you have complied with it, they would have to return the money to you (and if you, you could sue to enforce the policy).