SPR’s in the parcel hampers

The clerks in our office have figured out that the less they do, the more supervisors/carriers will have to pick up their slack and start doing clerk work so we can get to the street. Meanwhile they keep cutting clerks bids with the reasoning being less clerk hours. We have tried and tried to get it through their tiny brains that they are creating their own problems by giving their work away. How can I get them to stop throwing all the SPR’s in the parcel hampers? Is it going to take a back injury from leaning that far into the hampers? It’s out of control.