Steve, a true horror story and inexcusable for BMW sending the wrong parts. but, as I'm sure others will mention, the bright side if there is any, is that you or a loved one were not severely injured in the collision. Having a car in the shop for weeks is a real pain, but being in a hospital bed recovering from physical injuries is infinitely worse.
Hopefully it will be back to "good as new" soon.
Best of Luck!