Complex sentence: The first attempt at at mixing the album was done at Sarm Studios, London, but the band was dissatisfied with the result, so the album was re-mixed at Atlantic Recording Studios by Mick Jones and Jimmy Douglass.
Split into simpler sentences: The first attempt at mixing the album was done at Sarm Studios, London. But, due to the band's dissatisfaction with the results, the album was re-mixed at Atlantic Recording Studios by Mick Jones and Jimmy Douglass.