This poor customer service from SpeedMerchant has been going on for years, and the "spam filter" excuse is an old and tired one. That's completely unacceptable for any company, and if it were
an issue, it should have been taken care of years ago.
It seems as though he takes good care of his "team" drivers who continue to talk up the product and the company on the forums, while most of the everyday racers and consumers get ignored for weeks and sometimes months. Same story, different day. Go read the SpeedMerchant thread here back to the early days of the thread (more than a few years old) and Bruce has been continually a ghost with customer service.
I still own my Rev4, and I really enjoy the car, but if you are spending money on a 1/12th scale car, there are a LOT better places to look these days to find as good of a chassis with FAR better customer service and parts support.
Honestly, I'm shocked that SpeedMerchant is still in business with the way that customers have been continually treated over the years. In an industry this fickle, you can't treat your consumer base like that very long and get away with it.