2015 LEXUS GX Electrical System Problems

WE BOUGHT THIS CAR BRAND NEW IN 2015. SINCE THEN, WE HAD TO CHANGE BATTERIES 4 TIMES NOW. BACK IN 2016, WHEN THE FIRST BATTERY HAD TO BE REPLACED, THE DEALER ALSO CHANGED SOMETHING WITH THE STEREO, BECAUSE OF THE ELECTRICAL ISSUE. BUT THE PROBLEM STILL EXISTS. THERE'S SOMETHING WRONG WITH THE CAR'S ELECTRICAL SYSTEM, BATTERY SUDDENLY GOES DEAD. CAR HAS ABOUT 85,000 MILES ON IT. MOST RECENTLY, WE WERE AT A GRADUATION CEREMONY ABOUT 80 MILES AWAY FRON HIME, ON A HOT DAY, AND AFTER THE CEREMONY WAS OVER AT AROUND 2:00 PM, WE HEAD BACK TO THE CAR TO DRIVE BACK, BUT SUDDENLY CAR DIDN'T START. I HAD BOTH MY SENIOR PARENTS WITH ME AND IT WAS JUST A HORRIBLE SITUATION. THIS CAR IS UNSAFE TO DRIVE, BECAUSE YOU NEVER KNOW WHEN IT'S GOING TO LEAVE YOU AND NOT START. WHETHER IT'S SO MANY MILES AWAY FROM HOME...