Complex sentence: In May 2007, the RLPO announced that Petrenko had extended his contract with the orchestra to 2012 and in September 2009 a further extension, to 2015, was announced, with a change of title to Chief COnductor.
Split into simpler sentences: In May 2007, the RLPO announced that Petrenko had extended his contract with the orchestra to 2012. In September 2009, the orchestra announced a further extension of his contract to 2015, with a change of Petrenko's title to Chief Conductor.