Car Stall problems of the 2013 BMW 550

After having my BMW at the dealership for two weeks I had the low battery discharging message come on when I took the car home. The dealer also performed an oil change less than 1k miles prior to this problem. My battery died, luckily at exactly the time, I drove onto my driveway. The car just stopped. I'm just glad I wasn't on the highway or going faster speeds. I attempted to jump it and charge it but it wouldn't start. I had the car towed to the dealership and was told my engine had locked up and there were metal shavings in the oil filter and I need a new engine ($13,000). I don't know how this happened and the dealer can't tell me what caused this. I didn't get any warnings, car drove fine other than the battery discharging and your usual drivetrain malfunction message after the car wouldn't start. I'm trying to work with the dealership but I haven't gotten anywhere yet. This is a 2013 550i m sport with 72,343 miles on the car. The car has been kept up and is up to date on maintenance. I've read about issues with the n63 engine but I can't believe a car with 72k miles will just die. A car stalling out and stopping is not a good thing.