Even if you get new passports, DC won't stamp them for you. They will only stamp passports if you have old visas, and they anyway won't accept anything (not even corrections) after the end of September.
You'd better wait as much as possible to let them time to find your passport. If still not found, get new passports at your consulate and ask DC to return your money. However, if they find your passports and stamp them after you get new passports, the new visas will remain valid.
And it's always best to consult an attorney...
Good luck.