Sometimes I think VW CS like to mess with our minds. If you've been determined to have been a bit arsey with them they'll tell you BW51! Or, it really is BW51 but the dealer wants to keep your business, so he tells you it is still BW39. If you really are BW39 then you should definitely be getting confirmed on the tracker tonight or tomorrow as "build week confirmed".
At no point have I ever been arsey with them, I only called them because I had just sold my car and wanted to know that things were still on track, which they weren't.
According to the dealer it was showing as week 51 for 1 week then went back to week 39. He showed me on his system so either its true (for now) or he is playing massively complicated mind games.
Another theory is that although my BW has slipped I actually feel ok with it because its not BW51!
Maybe VW are playing mind games.
Or most likely is that they haven't got a clue what is going on and its all controlled by Klaus the cleaner in Wolfsburg

I am hoping it will go BW confirmed overnight but I thought it should be there by now.