I HAD MY BRAKE BOOSTERS REPLACED ON 05/22/2019.I WAS BACKING UP SLOWLY ON 07/24/2020 IN A PARKING LOT OF A CONVENIENCE STORE. AS I WAS BACKING UP, I TRIED TO APPLY THE BRAKES AND THEY BECAME STIFF. I TRIED TO PUMP HARDER ON THE BRAKES AND THEY WOULD NOT STOP THE VEHICLE IN WHICH IT WAS TO LATE AND MY CAR COLLIDED INTO A UTILITY POLE.