Here's two things to check to same symptoms with 140 PD last winter:
ECU software update. The original software was too low diesel to inject at cold starts because of emmissions. This cured my problem. Second, there's been many reports of ice/water in intercooler pipings here in Finland. Dealers cure for this is to drill a small hole to the pipe and get the water out before freezing (and getting to the sylinder!). And no, one small hole in the air pipe where huge amount of air flowing through does nothing to you power.
The ECU update came from Skoda factory but the drilling is maybe only local knowledge. Might be worthwhile to ask the dealer about these and then force them to ask the factory.