No hirer of a thing has a right to hire out the thing bailed to him to another person except with the consent, express or implied, of the bailor. If the hirer relets to another person without the consent of the bailor, the bailor may either take immediate possession of the thing bailed or waive this right and hold the hirer bound to extraordinary care and diligence on the part of himself and the hirer from him.
OCGA § 44-12-67