2005 Mercury Montego Shimmy in steering wheel

If it shakes when you apply the brakes and just had them done, then take it back. Tey may have just replaced the pads and not resurfaced your rotors or replaced them when they needed it. Or they may have contacted you about doing this type of work and you decided not to do it. Or the lug nuts could be loose on one of your wheels, that would be a good thing to check as you have it in your driveway.