When the mandatary is authorized to appoint a substitute, he is answerable to the principal for the acts of the substitute only if he fails to exercise diligence in selecting the substitute or in giving instructions.
When not authorized to appoint a substitute, the mandatary is answerable to the principal for the acts of the substitute as if the mandatary had performed the mandate himself.
In all cases, the principal has recourse against the substitute.
La. C.C. § 3007