There is most likely some sort of action you could take but it would probably cost significantly more than the airframe is worth.

As an Engineer by profession, I would say the vendor is right. The fact the airframe broke in the air is proof that the structural strength was exceeded . Of course the strength may well have been significantly low so as to render the airframe unsafe to use [&o]

Unfortunately there are quite a few ARF manufacturers that make some real junk then sell it cheap. It really is a buyer beware world out there. The suggestion to fix it and apply flying wires is a good one. I do feel sorry for your buddy and the hassle he is going to go through to do that.