1st off: do not overfill the resevoir. when the car is running (system primed) there should only be a thin layer of oil on top of the metal plate inside the resevoir. it should be impossible for the system to dump the oil out unless there is too much in it.
have a proper selespeed mechanic look at it. be weary of the average stealership. look around here for know good places. of you only got a alfa stealer near you (no expert) you need to tell them to do a full maintenance run on the system, adjust the clutch to 28.00~28.50mm and do a EOL and check out the pressure of the accumulator, see if it holds it's pressure properly between 45 and 55. that should take less then a hour. do let them do this on a hot gearbox. when doing this cold will give problems (jerky, bad shifts) when the box heats up. so drive up and let them go to work on it immediatly, don't leave it overnight.
Always cheat; always win. The only unfair fight is the one you lose.