Thanks for responses. I can't provide full detail (not my car etc) but the symptoms were binding up at parking speeds esp reversing with the wheel hard over to the right. I don't know why but this seems to be typical of haldex failure, right? The garage changed the pump to no avail, the info I have is that 'the diagnostics report diff failure', but I'm unconvinced mainly because mechanical diff failure is virtually unheard-of. In any case, the current garage want to replace the entire diff assembly, with either a new one or a scrap one. There is no obvious route to getting Skoda to do anything - it is out of warranty, and despite full main dealer service history the request for goodwill has been refused. There is no way to determine whether any negligence has occurred during servicing. No haldex servicing has been done except within the dealer service programme.
My questions are not related to diagnosis or blame. My questions are about treatment.
Given that the failure (whether haldex or diff) is within the diff assembly, it seems to me that you either take the 'mechanic's route' of replacing the relevant assembly, in which case the question is, are reconditioned assemblies available or is it just new vs scrap? Or you take the 'engineer's route' of stripping the assembly to fully diagnose and fix the problem, in which case my question is similar: does anyone know of anyone within the Dundee area that does this, and/or does anyone know if it's even feasible? To me it looks like very simple engineering but if for instance vital seals or bearings are simply unavailable, then that approach is dead in the water.