Hey Z... did you drive the car to the shop?? If so, was either rear tire tilting inward from the top side of the tire toward the center of the car?... cause... if not,  there shouldn't be a need to replace the entire bearing assembly... just the bearings... albeit, its a whoooole lot 'easier' to replace the assembly already set up(new bearings, spacer, axle, shim).. but, (always one of those), unless one of the bearings is in pieces, there isnt a need to replace the entire assembly...  just takes someone with a little 'know how' to replace and set up the bearings.

link to a picture of a bearing assembly(from the side toward the differential) 

http://www.corvetteamerica.com/cf/displayimage.cfm?partno=22351&imagename= Rear Wheel Bearing Assembly. RH&image=/images/catalog/products/item_22351.jpg