Best thing you can do is to make sure people here know who they are. Either they are cheating you out of your mats or they are inactive and in either case they should be removed from the list. It also is possible that someone here may be able to get in contact with them and they'll try to get your mats back or perhaps even what you ordered. Throw the name down here and let us know.
Outing people here is definitely the best way to go with that sort of thing. Worst comes to worst, if the mail is unopened, the mats will be returned to you in 30 days. If the crafter took the mats and *then* game quit, then things are a little trickier. Ticketing is probably the only recourse at that point.