The vehicle was towed into service department with a broken left rear axel, service department quoted and installed a complete used rear differential assembly, and failed to properly inspect the used differential which had a bent axle. After picking up the vehicle and bringing back the next day due to the left rear whhel wobbling, was told the replacement axle would be no charge, but we would have to pay for the labor to replace the axle. We were never given an estimate to replace with new parts and was not informed that the was no warranty on labor for the used part. We had no option but to agree to pay the additional labor to get the vehicle fixed and back into operation.