Studs shearing on new alloy carb mounts (1972 S2 Spider)

We have had a problem with a stud shearing on a new set of alloy Carb mounts that were fitted to my son's S2 Spider. These Carb mounts were supplied about 9 months ago by a very well known supplier of Alfa Romeo parts in the UK, whose name I won't mention right now.
The stud failed sometime within the last 6 months, after the carb mounts were fitted by a reputable and highly experienced Alfa Romeo specialist, back in May this year. This subsequently gave rise to some engine idling problems, seemingly where the carb mount was not sealing properly against the inlet manifold.
We've recently discovered that someone else had exactly the same kind of problem with studs shearing on new alloy carb mounts. Indeed his problem was even worse, as he had 5 of them shear on his Spider. His sorry tale is written up on the other Alfa forum, for anyone who's interested.
I'm keen to know if anyone on this forum has experienced similar problems, as the supplier doesn't appear to want to acknowledge that there is a manufacturing fault with these components.
I'll post up a couple of photos to illustrate the problem in a later thread.
Thank you,
Alan