So I had the same problem a lot of people had. The rear windows would not work from the switches on the rear doors irrespective of the position of the Window on/off switch in the master switch. However the master switch could roll up the rear windows without an issue. The problem identified by many is the Window on/off switch in the master switch. A quick way to confirm this was to hold down the window on/off switch in the master switch and then try to lift the rear windows using the switch on the respective door, if this works then the problem is confirmed.
Now the fix.. take the master switch out.. there is small hole in the arm rest put in thin screwdriver and push it down to push up the master switch.. then just pull it out and disconnect the wire. You will have to take the switch apart carefully... it is all snap fit and can be taken apart completely. You will find that the on/off switch has a staple pin like spring on the outside of the switch DO NOT LOSE this.. as it is the locking mechanism of the switch. This is the culprit.. over usage can lead to its legs spreading out and then even though the locking mechanism works.. the electrical connection to the rear windows does not happen and it actual stays in the OFF position although it looks as if it is in the ON position. The fix is very simple take a nose pliers and bend the legs of the the spring inwards and assemble the switch back and viola!! it works with no issues at all.. and you will notice the on/off switch has a stronger click and movement to it.. Hope it helps some one out there before they spend the $50 +++ on the part number 4B0 959 851 B 4PK or worse still if they go to a dealership for replacement...!!

 

I bought a new one from E-bay (seller in honnk kong) for $32 shipped I think

 

Thanks that was a 5 minute fix