Brake pedal goes hard

Hi ive just bought a secondhand grand espace privilege 2003 with 85,000 miles on the clock,its had a new clutch and cam belt fitted at 81,000 miles its in excellent condition in and out so for £1600 i bought the car . On inspection when viewing the car i noticed lots of grease inside front near side wheel which was caused by the cv boot being split so no problem i went ahead and bought the car..My wife drove it back 150 miles, on the way down a hill she flashed her light at me and pulled off the road saying she nearly ran in the back of me because the brakes failed.The pedal went hard right at the top with no braking power.brake fade !!!!!! After fixing cv boot and fitting new fads both sides on the front the problem is still there randomley hard pedal no brakes any idea what this might be and was there any recall to do with this problem does anyone know.....Ady Wimborne.