Looks like the gearbox itself has failed. The Dealer reports that they have now drained the oil and found metal in it and that the oil also smells 'burnt'.

One newAuto Gearbox coming up by the sounds of it. Approx £4,000GBP +fitting @£100 per hour plus VAT. Call it £6k.

I don't suppose I'll ever find out what really happened as I believe these broken boxes are recovered to the OEM and stripped to uncover the failure mode.

I'm now waiting to see if BMW GB will provide a replacement under 'goodwill', or this is going to be very expensive.

I'm also wondering if the odd noise the box has made from new changing between 3rd and 4th ratios is the actual failure as these two gears were in use when the trouble started and are exactly what I reported within months of getting the car. No sensor warnings then or now, just metal filings and burnt oil. Broken clutch/brake band? Anyone know what can cause filings and 'burnt' oil in these transmissions?

No idea when I'll get it back so far. Probably some time in the New Year.

Speaking of which - I wish all of the membership a Peaceful 2010 and that it's a better year than 2009.

__________________
Me:
Current: 2011 E71 40D Vermilion Red/Beige Nappa

Wifey:
Current: 2012 R80 Countryman SDX Green/Cream