Complex sentence: The band members declined the opportunity because they did not want to work for a major record label, and instead signed a recording contract with East London independent label Wichita Recordings, chosen because it did not want to stamp its agenda on the conception of records.
Split into simpler sentences: The band members declined the opportunity because they did not want to work for a major record label, and instead signed a recording contract with East London independent label Wichita Recordings. Wichita was chosen because it did not want to stamp its agenda on the conception of records.