I have a brand new Jones Homes apartment in Warrington. All three external stonecast window cills are cracked. Out of a total of 52 cills in the apartment block, 33 cills are cracked. Jones will not do anything about it as they say the cracks are cosmetic. I have arranged arbitration with the NHBC, who have looked at the cills and they stated that as the cracks are not structural, they will not get involved. Any suggestions where I go to next ?