Is the work being done by an actual company, or did the guy just speak to the one English-speaking representative of the illegals? "Can...you...fix....roof?"

If it's an actual company, you can file a claim against them. I'm not sure what kind of proof you'll need, but it can't hurt. Also, you may try asking your neighbor to keep an eye and an ear out (they might brag, or show it off if it's in a car or truck), and if they drive there themselves, you might check for a civic with a new fender.... matching body pieces has never been a high priority to illegals, in my experience. I even saw an IROC with like four different colors on it. Sounded horrible, too...

Just some suggestions; all hope --might-- not be lost.