Call them. Email responses are probably 24-48 hours away, for each email you send. By the time they get around to realzing the mistake, finding the right stock, and sending it out, you might be left very little ship time.
Also, for any new company I do business with, I always check the BBB site. No record means I'll at least look elsewhere, or be cautious with whatever I buy.
Mt Snow, VT - May 5, 2012 - Completed!
Gunstock, NH - June 1, 2013 - Completed!
...i remain, he who remains to be...