Unfair treatment in the work place.

FVS security company based in Port Elizabeth, working for Shoprite has wrongfully charged and arrested someone while all the evidence was pointing at someone else. While searching their security guards one of them was found with ****** goods but they decided to let him go and arrested the one that did not anything that was ******. The person they arrested is epileptic and spent the night in a cell without medication. I would like to know why the person with ****** goods was not arrested? Then they fired the other without consultation. How can I open a case against them for defamation of character?