Dodgy test?

Recently sent pickup for repairs and mot, within one month a brake pipe worked loose from hub, obviously lost brakes, brake fluid, going down hill at time, mechanic uses separate mot tester, however when questioned on it blamed me saying I took the car back too early, he'd did not have time to perform final check,(mot had been done an hour before I picked it up) he had the car for 8 weeks! Brake pipe was never secured to chassis, who is at fault, mechanic or tester, surley an mot is a final saftey check