I look at going to the BBB, which I've never done, the same as telling your credit card to look into a problem with a merchant. It's basically saying you can't deal with them anymore. I bet Sideshow would close the account too if a customer told their credit card company there was a problem. And the few times I've had to report a company to my credit card I've never dealt with that company again afterwards. It's like having to go to court or get a divorce or something. If you need a third party to work things out why would you deal with that person again?
But to me it should never even get this far. I would have been out as soon as Sideshow said wait a few months as a credit card will only back a purchase after a few months or so. If Sideshow said wait an extra few months for a replacement you are shifting away some of your rights as a customer and believing in a company's word that everything will be ok. Not the position I want to be in. And never has a company as long as I've purchased over mail order or the Internet ever said I would have to pay for return shipping on an item that was defective (the problem missed in quality control), damaged in shipping by improper packaging or mishandling in transit. They wouldn't have the nerve to tell me something like that. Especially if I waited months. Which I wouldn't wait anyways. And if a representative did, I would just ask for a supervisor. I wouldn't deal with the person that said something like that.
For people that did wait and Sideshow still didn't get things right. At the least, they should offer a $25 credit or free shipping on a future order. After all the customer did give Sideshow the chance to get things right.