Drivability issue with new rears

Haboob

So, since I've had new rears put on (it's been two weeks now)...

The RE760's made the car undriveable. 50+ I could not keep it in the lane, the car was just floating everywhere. They also took off the front wheels thinking I was doing all four, then put them back on - so not sure if something was damaged then.

Got S0-4's on and at first they put them (OEM size, rears) on the front wheels and tried to give me the car back, and I had to have them change it. The "floating" feeling is better, but still at 50+ under acceleration it's doing the same thing (just not as extreme). Corning is not as "on rails" feeling anymore, and there's a click from the front suspension every time I take off (say from a stop light, normal driving) or make a turn.

I couldn't find anything loose or the like in there, and Discount Tire can't find anything, and the alignment is perfect... I don't know what it could be that's causing this? Could a bearing be out? Could they have damaged it?

Any ideas?

Bastards also damaged my wheels, so I now have to go back in and be without my car for two days so they can re-powdercoat them.

Edit:

More info below:

OEM suspension.
OEM tire sizes.
Wheels have an offset of +27/+10.


I was running spacers prior to this (put on new, longer studs that came with) for about 6-8 months. Have had these wheels for about a year and a half now.