1998 Toyota LX470

SUDDEN TOTAL FAILURE OF VEHICLES (TOYOTA LX 470) PRIMARY BRAKING SYSTEM. VEHICLE TOWED TO TOYOTA DEALERSHIP EL CAJON TOYOTA) FOR DIAGNOSES. NOTIFIED BY SERVICE TECHNICIAN (CARLOS) THAT THE BRAKES HAD FAILED DUE TO A LOW BATTERY (8.2 VOLTS). RECOMMENDED THAT THE BATTERY BE REPLACED. I DIDN'T BELIEVE THAT A BATTERY, THAT HAD NEVER FAILED TO START THE VEHICLE, COULD CAUSE A TOTAL FAILURE OF THE PRIMARY BRAKING SYSTEM. HE EXPLAINED THAT THIS IS WHAT CAME UP WHEN THEY RAN THE CARS ERROR CODES. LATER, CARLOS CALLED MY WIFE AND TOLD HER THEY HAD REPLACED THE BATTERY AND THE BRAKES WERE WORKING FINE. I WOULDN'T ACCEPT THE CAR UNTIL I COULD SPEAK WITH SOMEONE, BESIDES CARLOS, ABOUT THIS. I WAS GIVEN JEFF THE SHOP FORMAN AND HE VERIFIED THAT THE WORK ORDER DID INDICATE THE BRAKE FAILURE HAD BEEN CAUSED BY A LOW BATTERY CONDITION. I ASKED HIM HOW A BATTERY STRONG ENOUGH TO START THE CAR COULD ALSO CAUSE THE BRAKES TO FAIL. HE EXPLAINED THAT THESE CARS HAD AN ELECTRONIC BRAKE ACCUMULATOR. I POINTED OUT THAT ONCE THE CAR WAS RUNNING IT RAN OFF OF THE ALTERNATOR AND NOT THE BATTERY. HE AGREED TO KEEP THE CAR AND DO MORE TESTING. HE CALLED THE NEXT DAY AND ADVISED THEY HAD BEEN ABLE TO GET THE BRAKES TO FAIL, WITH THE NEW BATTERY, AND THEY NOW NEEDED TO CHANGE THE ACCUMULATOR FOR $3,500.00. I ASKED THAT THEY GET MY CAR READY TO BE TOWED TO ANOTHER REPAIR SHOP. THE DEALER HAS REFUSED TO WITHDRAW THE CLAIM THAT A WEAK BATTERY CAN RESULT IN TOTAL BRAKE FAILURE. I NEED TO KNOW IF THIS IS TRUE O