I cant understand why they charge so much for the work either, 2-£300 maybe not 900-£1200. Let us know how much it costs you to lengthen both inner arms, and mod the outers, +fit 4x suitable rose joints and seam weld the arms and weld 2x brackets on the beam. On a fair wage yourself surely not £300 when you have a jig. good profit at £500 GBP a set? Best of luck mate