After over 4 years of trouble free motoring my Yeti clicked over 40k miles and it was recommended by my local dealer that I have the Haldex and DSG oils and filters changed.   This was done about 3 weeks ago. Since then I noticed an intermittent slight whine from the back end which I reported to the dealer. Not bad enough to take in and leave for a day and possibly end up with a £100 bill for investigation and they find nothing.so decided to monitor it.   Yesterday