Just in case this helps ( or NOT )
I Have unfortunately had a persistent problem with my drivers side window. As you say window drops half way down etc . and when I press the window up when it reaches the top it just bounces half way back down. I have been to several alfa garages and the guys there are having a hard time in finding the fault.
Firstly it was diagnosed as a controller isuue, but someone recalibrated the window and this seemed to work. Well only for a week or two . So I thought well it must be the controller. So I swopped this out and still the problem persist. So my second option was well it must be the Regulator and motor not functioning properly. ( I had already tried the 10 second reset trick to no avail )....
Regulator swopped out and still problem persists.
I then gave it to Alfa and they checked all wiring and they said everything was fine and the only last thing it could be was the DOOR ECU part no. 50510516.... From alfa this part is expensive but I was able to find it at a very good price. This is now coming in the post on 15 oct 2015....
I haven't tried disconnecting the battery though and should probably give this a go .
I will try this ( battery disconnection ) if this fails the ECU that's coming will be replaced. if this works I will be back to conclude . If not the search continues .
Thought id share, seings ive replaced a fair few parts already