Diet Patch Charged for something I didnt recieve Internet

They charged my bank account for something I didnt recieve and when I called them they said they showed it was delivered and I said that I didnt recieve it and they that I would have to send the patches back to get some credit but not the full amount, so I told them that I dont have them to send back and all they said that they showed it was mailed. I can I send something back that I dont have and then it wouldnt be the full refund. Very bad business for one they bill your account before you are suppost to get the product so theres nothing to do to stop the payment ahead of time. What can I do they charge like 89.97 which alot of money to some of us.