Sorry to hear of your problems at the dealership. Don't think it will make you feel any better, but this is a more common problem than you might think. It is not a dealership issue, but a GENERAL MECHANICS' issue more than anything else. No matter where you take your car or where you reside, all wheel work is 'supposed' to end with a torque wrench and a briefing from whoever hands you back your keys that you should either a)bring back your vehicle after 50 miles of driving to have all lugs checked, or b) check the lugs yourself after that 50 mile interval.
Now the 50 mile interval may vary by a few miles more or less depending on the shop, but it is used as a median number by mechanics worldwide. Truth be told though, how many times does anyone really ever see a mechanic check there 'lug work' with a torque wrench as they are supposed to do? More times than not, they just rely on the impact gun to finish spinning and call the job completed.
Hopefully no damage or harm came to you, your passengers, or your car because of this happening. It is something that happens all too often and should not!!