Andrew i feel your pain dude, ive seen many many cams snapped like that, some broken in to 5 bits, mainly 2.5 TDI T4s when the belt snaps
i would have thought you will prob have 8 bent valves, guides should be fine, so inesance its prob a few valves, a replacement camshaft, gasket set and bolts
when you ring piper make a point the engine has ONLY done 1500 miles and your not overly pleased with the way its failed, they may give you a replacement FOC, hell push for them to supply the gaskets, valves and bolts, defo worth a try dude
one thing tho, when you strip it down take a bucket load of pics, esp the timing marks, ive had it before on a T4 that dropped a valve, 40 miles after a replacement head had been fitted, i took pics of everything and once the head supplier had it he claimed it was timed up wrong so i forwarded on about 60 pictures to him, funney he gave a full refund within about 15mins of me sending the email