Peugeot Customer Service

My sisters 3008 (2010 56000miles) 1.6 Diesel, recently showed a low oil pressure light, she stopped immediately and I checked the oil, not too low but I topped it up and we continued home about another mile. Next morning after a mile, all power was lost and my assumption that the turbo had failed was proved correct when we arrived at the dealership. It took two minutes to diagnose that the retaining nut on the turbo impeller had come off. The dealer checked on the computer and came up with a nine page repair schedule, quite obviously, this is a known problem by Peugeot. The nut, it appears, is only held on because it is opposite thread to the rotation of the turbo, it is not secured by tab washer or lock nut or any other way.
It seems that the low oil pressure was caused by the blockage of the supply oil pipes to the turbo, this caused the turbo to stop rotating and the nut then went south, never to be seen again. The value of this nut is approximately 50p, the cost to repair the car is £2000.
All this on a vehicle which has been regularly serviced by Peugeot. I raised this issue with the complaints department as to why customers have not been informed that such a catastrophic failure can happen without warning, and why have Peugeot not accepted any responsibility for such a bad engineering design. To date I have no success, only an offer of £1000 off a new car.
To all owners of this model, I would advise getting your car checked by Peugeout before this happens to you.