Yes I did have the key, and they are the original bolts. I suppose they must have been overtightened, but surely not by that much. Also as far as I know the rear wheels have never been off the car so this could only have been done by Alfa pre delivery. Surely the tool they use for inserting wheel bolts is set to the correct torque.
The one on the passenger side came out on Thursday with ease, but the guy just couldnt shift it yesterday. I know when it was put back in it wasnt excessively tightened as I watched the guy do it, and he knew he was likely to be in line for removing it again very shortly.
I still think the design is poor. I do wonder how many people are driving around out there in the same situation, blissfully unaware of the problem. Imagine the annoyance when the minor irritation of a puncture turns into a complete nightmare as you cant get your car home or to a garage.