Glanga, Sorry to hear about your problems, sounds likw what always happens to me when I take my car in,
When my car smelled of burign oil and started misfiring I took it in knowing it was the valve cover gaskets, and obviously one of the coils were beeing flooded with oil. SO I took it in and they replaced the driver's side bank. replacing one coil, and the gasket. They also did my ball joints, faulty drivers side door handle, and gave me anew 6 disc because cds wouldnt play on it. 1700 dollars later, (1300 of which my aftermarket warranty paid for) i was on the road.
The drive home my dad (in his GMC envoy) decided to be funny adn "race me" from a light, so of course I hit it expecting to embrass him and his straight six beast, but my car starts jolting and sputtering. WTF?!? i said to myself, the envoy even beat me for the car was misfirng soo bad. next light i smelled that great smell again. burnt oil. NOT EVEN 5 Miles form the dealer and the problem was still there, after three days of being fixed too. One of the mechanics, when putting the gasket on, accidently rolled the corner or it broek off or some BS story, so it started leaking again.
I took it in a while ago for my graning wheel bearings, and they kept it for a day to diagnose and get back to me.( i dropped it off right beofre they closed.) picked it up the next day becuz I didnt want to pay 1700 dollars for new bearings/knuckle install, and i noticed they pit 12 miles on my car but used 35mi worth of gas. hmmmm ALso the tech when handing me my keys siad, "we all love that exhaust" i bet you do guy... I specifically told them how the noise sounded, where it was coming from and at what speeds, so why the need for a 13 mi test drive?
sorry had to vent there, but hey I still love my LS, but I think if I had a cts-v i may have the same opinions as you towards the LS. But i dont have a cts-v, and i prob never will. SO good luck with this problem, and just bitch at the dealer, they screwed up so they shoudl fix...keep us posted