bad handling round bumpy corners

the whole car seems to jump sideways when you hit a bump going round a corner (like a scared cat).
it also does not seem to take potholes very well on the straight either! lots of juddering and shaking!
The garage says that everything is okay and that the suspension and bearings, ball joints etc are all very tight. no wear.
am having the tracking checked out today as its eating tires on the front inner rims.