I have a small business & recently discovered shoplifters on cctv they got away of course before we could call police. But then called my shop few hours later for non-related questions. To late to prosecute , but want to ban from coming back.

You can still report the theft to the police and provide them the tape. Then if the people come back, contact the police and let them know the shoplifters are in the store so they can be arrested at that point. If they have been in trouble with the law before, the police may even recognize them or be able to connect them to similar crimes in your area. Part of their job is to try to figure out who they are and find them.

I've heard of shops printing pictures from the surveilance tapes poster size and hanging them on a "wall of shame".