2013 LEXUS ES350 Electrical System Problems

I PURCHASED THIS VEHICLE BRAND NEW FROM SEWELL LEXUS IN FT. WORTH TEXAS IN SEPTEMBER 2013. SHORTLY THERE AFTER IN LATE OCTOBER, I WENT TO START MY VEHICLE WHICH IS PARKED IN MY GARAGE. THE CAR WOULD NOT START, DEAD BATTERY. I JUMP STARTED IT AND IT STARTED RIGHT AWAY. THIS HAS HAPPENED SIX TOTAL TIMES IN THE PAST YEAR. THIS MAINLY HAPPENS WHEN THE CAR SITS FOR MORE THAN 2-3 DAYS IN MY GARAGE. I HAVE NEVER LET THE CAR SIT MORE THAN 5 DAYS, BUT WHEN I DO LET IT SIT FOR 3-5 DAYS, THE BATTERY IS DEAD. CURRENT MILEAGE IS AROUND 4200. I TOOK IT TO THE DEALER IN SEP. 2014. DEALER COULD NOT FIND AN ISSUE AND SAID THE BATTERY IS FINE. 2 WEEKS AFTER I LEFT THE DEALER, MY VEHICLE BATTERY DIED AGAIN. DEALER RECOMMENDED A NEW BATTERY. A NEW AFTERMARKET BATTERY (INTERSTATE) WAS PUT...