W124 brake squeal, still

[jbach36]

Just had my brakes redone after they FAILED about a month ago. Had a hard pedal, overshot a stop sign by 15 feet, could have killed someone.

Had my brakes fixed (new power booster, new hose, new pads, new rotors), but now the brake squeal is back when I come to a near stop. What causes it (I heard it's very tiny, very fast vibrations of the pads against the rotors), and how do I get rid of it.

Thanks,

Jeff 1991 300d, 101k