Here is what I think happened to cause your forks to collapse.
Pictured are the parts from the fork cap down. The cartridge is not shown and the spring is from Race Tech. The large washers at left are placed on top of the spring (right end of spring) the tube spacer comes next followed by the nut and fork cap. The damper rod goes up through the center of all these parts and holds everything together. The washer with the larger hole in it came from Race Tech and I used both it and the stock washer at both the top and bottom of the spring.
There are two identical washers located at the bottom of the spring (not shown). They are placed between the top of the cartridge and spring.
Aftermarket springs (my experience is with Race Tech) are larger in diameter than stock. Race Tech provided large flat washers with their kit and I used both these and the stock (smaller washers) to support the spring at each end. If the shop that did your installation did not use enough (one large, one small stock washer) (or strong enough) washers it could cause the forks to collapse. I think that the washers they used failed causing the spring to bypass the spacer and hit the bottom of the fork cap.
The washwers between the cartridge and spring could have failed as well and could have jamed the spring on to the cartridge assembly possibly damaging it???
If I were you I'd want pictures from the shop of how they are going to "repair" their mistake. Which, by the way is a real **** up and inexcuseable. They should be kissing your *** at this point becuase their installation could have caused your death/injury etc...