I've had this sort of "unrelated" repair right next to something a contractor was fixing on multiple occasions, too. It's hard because you're at their mercy. . .up to a point.

Your recourse is probably not legal, but you can sure spread the bad news online and elsewhere. Meanwhile, find someone else to do the repair and dispute the charges for the current repairs. At the very least that first repair had nothing to do with the problem.

And document everything you can.