Complex sentence: Colin later clashes with Gavin after his promotion to Acting Deputy Manager out of jealousy, but Brittas later reveals that Colin is still regarded as Deputy Manager Wet and Gavin's superior, much to Colin's delight and Gavin's chagrin.
Split into simpler sentences: Colin later clashes with Gavin after his promotion to Acting Deputy Manager out of jealousy. However, Brittas later reveals that Colin was never actually terminated as Deputy Manager Wet and is still technically Gavin's superior, much to Colin's delight and Gavin's chagrin.