SSBC Returned Items (No Refund and Now Being Ghosted)

I have no experience with them.
That said, how did you pay? If you used a credit-card you can likely initiate a charge-back. It may get SSBC to speed things up by mentioning you are going to pursue a charge-back.
I would typically expect 4-6 weeks for a moderate sized business to do a return/refund - but it's now going on two months. There is also usually a window for being able to charge-back on a credit card, and you may want to inquire with your card issuer to find out if you still have the option.
Paid via credit card. I have gone down the path of what you explained as well. I opened a case with my card company a little over two (2) weeks ago, providing all the proof of purchase, proof of delivery, etc documentation. I even explained to them that I'm not even looking to recoup the full cost of the brake system, as the SSBC website states there is a 25% restocking fee. It is not difficult to figure the cost of the refund (cost - (.25)(cost)) = refund. I didn't understand why the last time I was actually able to speak with someone at their office, the guy made it seem like it was rocket science. At this point I am working all angles.
When I was on the phone placing the order for the system, the transaction to charge my card was done in a matter of seconds while I was still on the phone. I'm only expecting somewhat of a similar effort/courtesy when it is time to refund a person's money.