2000 Toyota Tazz Just Had Car Services Mechanic Who Did Following Major

I have just had my car services at a mechanic who said he did the following, Major service,fit new cambelt and guide fit camshaft,oil seal,fit new left rack end and boot,fit new rear front outer cv joint,fit new regulator on alternator. R3000 later and my car has a terrible rattling sound at the rear and when driving at a speed above 100km and press brakes the car shudders badly.

What am I to do now