Complex sentence: In 1993, it was sold to Susquehanna Radio Corporation--which has since been purchased by Cumulus Media Partners--and changed call letters to WGRL and adopted a country music format.
Split into simpler sentences: In 1993, it was sold to Susquehanna Radio Corporation--which has since been purchased by Cumulus Media Partners. It then changed its call letters to WGRL and adopted a country music format.