Alternator/generator/regulator problems of the 2012 BMW X5

On July 31st 2017, the bolt securing idler pulley and alternator sheared. Battery charge malfunction light came on followed by loss of power steering. Looking at my service record, I see that this same bolt was subject to a recall in January 2013 when car was at 12332 miles. The car is now at 63456. Also noted on BMW owners web site that many other owners of this e70 series design have had the same repeat problem. BMW dealer in CT performed the latest repair and offered no explanation, except that their work is guaranteed for 2 years. Original recall performed by dealer in raleigh nc where car was purchased new has advised me to post this report and call Bmwna. I am waiting to hear back from them, but first discussion was not good. They claimed that they did not have a record of this as a continuing problem and would not be able to give me any assurances that it would not happen again. I note that the part number of the new bolt just installed is the same as the old bolt installed in 2013. We were very lucky not to be involved in a serious accident and without some clear assurances that BMW understand how to fix this continuing problem I am very worried about driving the car. At the time of the bolt failure we were driving at about 20mph through the center of the town of stratford CT and just managed to pull off the road into a train station parking lot.