Complex sentence: She worked on the show until the station was rebranded as Smooth Radio in March 2007 and has hosted Smooth's evening show since then, until March 2008, when she left Smooth and Steve Merike took over Smooth Evenings.
Split into simpler sentences: She worked on the show until the station was rebranded as Smooth Radio in March 2007, where she then hosted Smooth's evening show. However, in March 2008, she left Smooth and Steve Merike took over Smooth Evenings.