A "core" is (with the exception of typically replaced or "renewed" parts) generally in the same physical condition as a serviceable unit with no missing parts, no cracks to the housings, all necessary internal and external parts that deem it a "complete" unit must be present.
Phil, chew their asses, demand the cores back or partial credit.
Any REPUTABLE shop will send back what they call "junk", or at least give a partial credit.
Mark.