Engine Oil Leaking problems of the 2009 Volkswagen Jetta

Engine rear main seal failed on 80,000 miles. Engine oil leaking.

I had my 09 tdi towed into a v. W. Dealer today for a major oil leak. The details are as follows: I parked my tdi in my driveway this morning after a local drive. No mechanical problems were observed. In the afternoon I went for another drive. I barely got out of my driveway when the cars oil light started blinking, and the mfd said stop the vehicle-low oil. I pulled back in my driveway and noticed several liters of oil on the ground under my car. I had my vehicle towed to the dealer by a flatbed tow truck. The service manager called me into the shop and showed me that the oil filters housing cap had been screwed loose, and placed on-top of the housing upside down. The cap had a small piece missing just before the threads begin. Since the car had 1 1/2 quarts of oil still in the oil pan the service manager did not feel that any engine damage occurred. I explained to the manager that I had been home all day, that my car was locked, alarmed, and parked in my driveway. The manager insisted that someone did this damage to my vehicle. He could not explain how someone was able to get in the vehicle without the key, and without causing any damage or leaving any tool marks, or setting off the car alarm. I had my vehicles 10k service done at this dealership 800 miles ago. During that service the wrong oil was used, and the vehicle was severely overfilled with oil. These problems were caught by myself, and corrected before leaving the dealership. Is it possible that the dealer caused a third problem during my 10k service, such as not properly tightening the oil filter's cap, or was my vehicle vandalized by a mission impossible impersonator? is it probable that engine damage occurred to the vehicle? if what the dealer said is true this vehicle has a severe security flaw!.