CRIME reported on flight and nothing done!!

Myself and my fiance witnessed a crime on the flight and NOTHING was done, this is a major concern for safety flying on your airline. We witnessed men digging in bags in the overhead lockers whilst passengers were sleeping, which went on for about 2 hours!! I was told the Captain was made aware but they walked free off the plane!!! Disgusting as what about the safety of the passengers who had their bags dug in!! This makes it look very suspicious. SAA do not protect their passengers!