Meter box

When I moved in a complex the guy that brought my meter box to install said I would get my R500 if I give them back the meter box.I left the meter box in the old apartment so when they come install for the new tenant they take mine like instructed by the guy that set the meter box for me.now they telling me I should tell the agent or sell it to the new tenant. The agent says no cost was added for the new tenant and it not her business that tenant used the meter box impact as they not the same company,also telling me it is not their business. When installing hire staff that has knowledge because I could have moved with my meter box as I use impact here now ,I lost my money have to pay for another meter box her.