91 100 auto tranny trouble

[DGraber460 at aol.com]

To my horror, my wife reported that the transmission in her car seems to be 
on the way south. It has started to whine (very high pitched) and shift 
erratically.
I haven't read many of the tranny posts, as most are for manual swaps etc. 
The posts I have seen have left me with the impression that I am in trouble.
The car is in great shape, and I am not ready to let it go.
The car has the "sport" mode auto box.
Are these repairable? If so, where and how much? Are the units coming form 
Germany recently Quattros only? Anyone know of a source for a donor unit?
TIA

Dennis
Denver