Did you use a credit card? There is a nice buyer protection feature built into most credit cards, its two little words I like to use when I don't get my way, its called... charge back.
Since they sent you a cam that isn't what you asked for, you should call the bank that issued your CC, tell them that you were sent the wrong thing and now the merchant has left you high and dry, won't return any calls, and you want to chargeback for $xxx dollars you spent. I don't make a purchase unless it's with a credit card just so I don't get hosed. I've only had to charge back like once or twice, and it was for situations like you're in but even worse where I just never even recieved my parts.