99 a4 tiptronic upswitch fault message

On my 99 a4 quattro 2.8, at a garage there was a fault message for the tiptronic upswitch. Symptoms that I have experienced are the manual tiptronic will upshift, but it will not downshift. When I upshift through the gears, it will only return to first gear by automatically resetting itself at a stop. After a cold start the automatic trans will hang in first gear for about 30 seconds. Any thoughts/suggestions as to what I'm looking at?