Missing keys...

I was renting out my property in Reyno Ridge Witbank. I gave the keys to an agent from 1St Net Properties who said she will find me a tenant. The property was vacant for 2 months after which a managed to find a tenant myself. When going to get the key back from the agent she realised that the key was missing and she had no idea where it was as she gave it to a number of other agencies who claimed they had possible tenants and in the process completely lost track of my keys. I then went to the property and realised that someone had already moved in without the 1st Net agent or my knowledge. One of the other agents that she gave my key to had made copies of the key, rented the property out and I did not receive a cent, instead I had to replace all the locks in the unit as a safety measure as my original key is still missing and who knows how many copies were made.