Delica had engine stripped and inspected in march 10. Extensive work done; R&RHead, Rings, Big End Bearings, VRS Kit, Oil filter, Timing Belt Head Works, removal of sump and pistons and installed new rings, honed bore Dec. 10 (9 months later) advised pistons need replacing. Is mechanics workmanship questionable? Am I in my rights to ask him to rectify? Thanks.