The noise should go away within a few hundred miles or so. The squeal is common if you change pads but not rotors. Sensors cannot be used once the red light comes on. Did he check your rotors for minimum thickness?

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'06 X5 4.8is, TiAg/black, cold weather pkg., comfort seats
'07 750Li, TiAg/black, sport pkg.
'05 Ford F350 silver met./slate gray, Lariat, 6.0 PSD, CC, DRW, FX4