Front Suspension Stabilizer Bar problems of the 2010 Hyundai Santa Fe

My 2010 Hyundai Santa Fe limited awd 3. 5l, with approx. 60,000 miles, was making noise in the front end when I went over bumps or rough terrain. A local dealer told me it was most likely the end links going from the struts to the stabilizing bar. Two shocks were leaking so I had the struts (front) and shocks (rear) replaced along with the end links. On a test drive it was still making a clunking noise so I research the Hyundai forums for possible causes. There were four possible causes, one which had been corrected, the end links, the lower control rod, the connection mounts between the frame and the body, and the front and rear engine mounts. Upon inspecting the engine mounts I found the front engine mounts bolt, a 12mm x 5 inch bolt, missing. Apparently when the car was engineered the bolt wasn't secured with a locking nut or cotter pin so when the nut loosened and vibrated off the bolt, the bolt also vibrated out of the mount. I actually remember when this occurred, at around 50,000 miles. I remember a loud bang under the car and in the rear view mirror I saw a bolt tumbling down the highway. I thought I had run over it with a wheel. I took the car into the Hyundai dealer at 56,652 miles for an oil change and "12-point inspection" and "multi-point inspection" and the mechanic didn't discover the missing front engine mount bolt. (I found it myself when I took the car to a local car shop for the strut and shock replacement. ) I then went to the Hyundai dealer and told them what I discovered. The part number for the bolt is 21920-2b000, and the part number for the nut is 13396-12007k. There was no description as to the size of the bolt, the thread of the bolt and nut, nor whether the nut was a locking nut. I had the local mechanic make the repair with a 12mm x 5" galvanized bolt with washers, lock washer and a 12mm nylon locking nut. I consider this a safety issue.