I've had a 2012 4x4 dsg 140bhp Yeti for the past two years, now at 75k miles of which I've done 40k miles.  For pretty much all of those there has been a whining sound which appears to be coming from the rear of the vehicle.  Changes of tyre brands have made no difference. 

 

The sound is particularly noticeable when I release the throttle pedal  and the car loses speed from 100kph to 80kph, and is especially bad at about 90kph.  If I press the throttle on and off during this as the car is decelerating the sound comes and goes.  On rough surfaced roads it's not too bad, but it's really loud on newer and very smooth surfaces.

 

I've had Skoda do a diagnostic and they couldn't find anything and the car has just passed the NCT (DOE equivalent).  Has anybody else experienced this noise or have any ideas what could be causing it, bearings/diff/haldex ??

The Haldex is due its 2nd Oil Change (Service), 

and has the DSG had one OIl change and getting its 2nd one soon?

It's fully serviced and by that I mean everything, haldex and dsg included. The noise existed before I had those done a year or so back and was still there after. Unless of course the garage didn't actually do them, but I doubt it.

Haldex service due at 3 years, so that would be 2015 and 2018.  DSG @ 40,000 mile intervals so even if full main dealer history check they were done.  Service plan might not have had it carried out.