I heard it happen on Boxsters before, but by no means is it a common failure as far as i've read. Same thing happened on my dad's Merc while driving. The thing let go with an almighty bang and the front of the car dropped. Lucky we were only doing about 10mph at the time after pulling off the motorway. Again he had the battle with Merc. They would fix the suspension under warranty but not the secondary damage to the wings caused by the front of the car dropping onto the suspension bump stops. He had the battle for a few weeks and after telling them where they could stick his car and he'd rather have his money back they agreed to fix it.
The thing that horrifies me with these things is the companies utter lack of interest when a potential safety issue like this happens. In my line of business following a failure of this nature we would be obliged to investigate the failure and understand the cause and take appropriate action to ensure it wasn't a risk to other products out there. Merc showed no interest even though minutes before we were tanking along the motorway at a decent speed. Unfortunately these people seem to want to wait for a death to occur before they stand upto their obligations.
If the polite and gentlemanly approach fails with the dealership you could always wait till the showroom is nice and busy then go down and insist on having the debate in the showroom in front of all the potential customers.
