Dispute that charge with your credit card company. Fill out the appropriate paperwork and include a typed up list of what you did. The card company will review and issue a provisional credit (usually) right away. They will investigate, and with your list of replies and bogus emails, they will side with you. Credit card companies are usually pretty good about taking care of this type of stuff (have been for me at least). The vendor stands to lose here IMO.

I bought a carb for an atv a while back and got the same kind of run around. I declined the charges after fighting with the company for a week and a half. They shipped the carb but it was too late for me, there are hundreds of vendors out there and after being treated like that, I wasn't giving them any of my money. Carb showed up and was left on the doorstep (after I disputed). The company was pretty peeved about it and wanted me to pay the shipping to return it. I never paid shipping, never returned that carb, and they never got paid either.

I would have been willing to return it had they sent me a postage paid box or scheduled a pickup but I wasn't going out of my way for them when they clearly wouldn't do it for their customers. I explained all this to the credit card company and they were very understanding. I would go the same route on your purchase, just jump through their hoops and they probably will set you right.