Has anybody dealt with a Company called Mastergrade?

Here's their address:
Mastergrade,
1442 33rd st.,
Signal Hill,
CA 90755,
USA.

I bought a set (4) Brembo cd/sl. rotors from them bl**dy ages ago (jan/feb this year) and still haven't recieved them.
I had corresponded with them by e-mail (as I am in France) but still no joy
...and now they have stopped replying to my e-mails.

Please, please, please, can anyone suggest what I can do
...or act on my behalf.
(I have the original sale papers).

I would appreciate any help at all.
Thanks.