2016 EQUINOX ROLLED BACK 15-20 FEET, DESPITE THE VEHICLE BEING IN PARK. CAR WOULD NOT STOP ROLLING BACK AFTER ENGAGING THE BREAKS. APPROXIMATELY $12K OF DAMAGE DONE TO MY VEHICLE, AND $10K IN MEDICAL, AND ANOTHER $5K IN PROPERTY DAMAGE TO AN APARTMENT COMPLEX MAIL CENTER. POSSIBLE MECHANICAL FAILURE WITH TRANSMISSION AND/OR BREAK SYSTEM. BRAND NEW VEHICLE; NO ALTERATIONS MADE TO THE VEHICLE AFTER PURCHASE; FOLLOWED ROUTINE 3K, 5K, 10K AND 15K MAINTENANCE SCHEDULE.