Unfortunately VW can't elaborate and what caused the failure as they have said the box is sealed so they have no way of telling, all they will say was that there was no oil in it.

Whether lack of or low oil was the cause of the failure or a result of the hole caused by the failure will probably never been known.

As Listers were the only people to work on the box, albeit it at 48k not the VW recommended 80K, it could make you wonder if they added the correct amount of oil, or even the right type of oil!
I will most certainly not have any dealings with them again. Shame really, as a courtesy call from them after the initial fault had been made known to them, would have been appreciated.