A system for securely controlling deposition and retrieval of shipments (40), including a managing distribution centre, at least one electronic locker unit connected to the managing distribution centre through a communication network, and having several lockable compartments (28i) of different sizes, wherein said at least one electronic locker unit comprises a weighing shipment module (50) located inside each compartment (28i) and made up of an arrangement of several thin flexible force sensors, linked together to circuit board, located under upper bearing plate and attached to bottom of the compartment within respective active measuring areas.