Complex sentence: This lineup continued as ATHLETICO SPIZZ 80, gaining a considerable following, they became the ONLY band to sell out the Marquee Club for five consecutive nights (and a sixth afternoon alcohol-free matinee show).
Split into simpler sentences: This lineup continued as ATHLETICO SPIZZ 80, gaining a considerable following. They became the ONLY band to sell out the Marquee Club for five consecutive nights (and a sixth afternoon alcohol-free matinee show).