If an actuator for a new turbo is altered by the mechanic, the warranty is gone, just like that. In order to move the actuator's threaded rod, you have to loosen at least one nut. If the nuts have been painted and you move them, the paint cracks. No warranty. That's why they paint items on the turbo; so they will know if you try to mess with the settings.
My next question is, I've never seen those screws 'fall out', as they usually get so hot they stick in the holes. So, why were they so loose, the actuator fell off? Did they rot off? Maybe then, you needed the turbo. I'd like to see that old turbo. Apparently, the actuator was still on the end of the vacuum hose. I would have checked to see it it even worked before searching for a new one. Although you didn't find one does not mean you can get a new one. I have them and can access them online.
Then, I have to ask... One day, did you not suddenly notice that your car became completely 'gutless' and would hardly get to 60 mph in 2 minutes? That would be the day your actuator fell off. Either that, or did you now know when you bought the car, the turbo never worked?
Last, why would the mechanic send you home with a new turbo that has no boost? Does he know what they are supposed to do? What kind of mechanic works on a car that was weak as a kitten, then sends you home with a new turbo that apparently made NO DIFFERENCE! If he claims to be a mechanic, how could he not know?
If nothing else, I'd find a new mechanic.
