USBI Unauthorized Charge Miami Nationwide

This company charged me without my authorization or knowledge. Their charges were supposedly for international calling plan and they charged me to my at&t account. I do not know how can At&t charge me this without me authorizing. I called USBI and they did not want to credit my account for the charges they added to my phone bill. If i wouldn't have called my telephone provider i wouldn't have known about this charge and i would kept getting charged. I don't understand how something like this can happen. A company that is full of scammers like this one takes the hard earning money from consumers like me. I hope the authorities can get to the bottom of this and this company can stop scamming other hard working people's money.