This is a sad story,but from a practical point of view would the OP have been willing to pay the cost of a replacement on recon engine and turbo's in the first place - had it been correctly diagnosed ? Seeing as it came in as a non runner they would have been unable to carry out an oil pressure test anyway. The Turbo drains on these engines are known for clogging, and also sludging up of the sump is another issue. Was the OP willing to pay for the engine to be stripped and checked prior to fitting turbo's ? Would he be willing to pay for replacement EGR coolers which, when they leak often cause the turbo's to clog and fail.
What needs to happen here is an independent third party engineer is brought in to inspect the engine and turbo's to negotiate a sensible settlement. Either way had the extent of the damage been known in the first place the car would most likely been scrapped. Its all too easy to sit at a computer and flame a garage when you don't have all the info,in some ways they were very brave to even get involved in the first place, I can't imagine they are too chuffed about it either.