This is incredibly common on the FFG/Z series that use this style heel. I'm actually surprised so many people are saying you are shit out of luck. I dont see any indiction you've pulled the screws out or bent the heel track, mind you I'm only looking at two pictures.

Tthe cracking almost qualifies as cosmetic, the part you have broken is just a casing, the screws hold the metal heel track almost exactly the same without them. Its not good and you shouldn't ski on it, but people do all the time and never have a problem. Any salomon or atomic dealer should be able to order the part for you.

I'll try to explain why this isn't that bad. They way this binding is designed with the front heel screw go through the track and the rear screws set tight against the sides of the track with the tops of the screws over the sides to keep it down. This allows the track of the binding to slide under the rear screws as the ski flexes. I'm not sure if this is by design or not (I imagine it is as knee bindings markets this 'feature' heavily). The down side of this 'feature' is that the housing not held in this way and is forced against the screw cracking it in extreme circumstances.

If only the housing is cracked the name of what you need is: Plastic Heel Guide Housing L308425001 Definitely dont pay more than 6-8 dollars per guide.

Now if your heel track is bent you have slightly more expensive problems. You now need (Steel Heel Track) L0011730001. Dont pay more than 15ish per track. Your screws are most likely bent/pulled out a bit in this scenario as well which means either heli coils or moving the binding at least 8 mm from the edge of any damaged part of your ski.

Figure to pay at least the price of remount on top of the parts from your local shop, if you go heli coils you will probably bump the price up significantly.

Depending on the ability of you to install the parts your self this can be kind of a pricey problem.