You shouldn't tarnish DoctorDiff's name by mentioning him in the same sentence with SSBC. DoctorDiff is known for having great parts AND great service. SSBC is known for pretty much the opposite, and has been for quite some time, even before and after going bankrupt and being bought out.
SSBC's kits also include parts that you can't get off the shelf, so if they go out of business again you'd have to source your own machining to replace your rotors. DoctorDiff's kits pretty much all use off the shelf parts for their wearable components, with only the non wearing parts being custom. A better set up all around.
The CC company will usually try to follow up on the transaction. Also, just have the charges reversed. SSBC has your money and your parts, their re-stocking fee is their problem and if they're not going to refund your money in a timely manner it's not your problem to dictate to the CC company their re-stocking fee. It's easier to just reverse the charges. If SSBC was worried about the restocking fee, they should have handled their business.