Bulk meats losses

Bought a rump and loin for R86.95/kg. Had them processed my meet as this is part of their service and deal when buying bulk. The meat originally measured 23,5kg When I received the meats I weighted them in at 17kg which means there is a loss of 25%!!! My so called R86.95/kg was now R120/kg. This includes mince and boerewors which they sell at R110/kg over the counter. After consulting with 3 other butchers, they all claim that you can lose anything between 9-13%. I lost about 5kg of proper red meat. (Rump/Sirloin) I went back to argue about the weight by the butcher just told me that is how it is, if I'm not happy I can return the meat. I think this is bad service, ripping you off when buying bulk.