2000 Other Alfa Romeo Models Repair after MOT

Got alpha 2.5 v6, had it mot'd, needed top right arm replacing, steering rack, brake discs and pads. Had it all done by alpha dealer, day later it starts knocking on the right side when turning the wheel left or right and when about to start driving from first gear into second, could feel the steering juddering, on a couple of occasions the steering wheel jumped out my hand and went the other way, when breaking heavey in traffic the car clonked really loadley. I took it back to the alpha dealer, now they are saying that the bottom right hand susupension needs changing because the brushes are perishing the suspension. I would like to know did they cause this problem to happen, as it was not knocking before they did their work on it? And if they did should have to pay them for having to repalce the bottom arm?