Sounds very much like what was wrong with my sisters car - a mysterious oil leak. The oil kept leaking out of the system somewhere but no idea where too. Never any oil on the drive or anything. Oil eventually gets so low the gears wont select.
parts £1000 under warranty
Yep, so after having the actuator replaced 2 months ago, I'm now told the new one is faulty and leaking..... Covered by warranty though, but still labour to pay......
Now I'm not too impressed by all the selespeed abuse in this thread, but I do indeed suspect it has not been manufactured as robustly as such an expensive component should have been, shame on the maker for that.
I love my Alfa, but it's quite tough getting used to a car that has such regular and high maintenance costs..... But I did my research before buying, and I knew what I might be in for, so I'm NOT going to complain too much about it, it's certainly a fabulous system when working.
But two in two months is either really bad luck or really bad quality control, and from what I see, I do have to suspect the latter.
But more than anything, I just want my Alfa back!!