Discovery 4 Crankshaft Failure
The bad new is crank issues with the Landrover Discovery 4 are too common, and even on the later models it not unheard of for total engine failure. If you intend to take the Discovery back to Land Rover they might change the full engine, but just swap out the turbo or even the head (if within the warranty). Unfortunately they are rarely the same vehicle even after Land Rover work on them.
The good news is, if you want further information on this issue or even attempt a repair yourself, you can download the Land Rover Discovery 4 Repair Manual here.