Complex sentence: Warneke often acted as a substitute on Neil Mitchell's morning program on radio station 3AW, he was at the helm of the show for many big news stories, including the Port Arthur massacre and the 9/11 terrorist attack on America.
Split into simpler sentences: Warneke often acted as a substitute on Neil Mitchell's morning program on radio station 3AW. He was at the helm of the show for many big news stories, including the Port Arthur massacre and the 9/11 terrorist attack on America.