you're probably one of those people who do not double check their grocery receipt and just stuff it in the bag along with the groceries. you should check what was done and ask for the replaced parts back. chances are it wasnt the whole sway bar but just the end link was reattached but not bolted in, when they changed your struts. always check, even just for tire changes and such. my friend had his tires rotated last summer. he didnt find out till he got home that the right rear tire's bolts were not tightened !!!
by the way, your sway bar/s hold the car level when you do those tight left and right turns.
regards