I also have the RCI Platinum. When we had to recertify our junior dragster belts, I had to send them to M&R in New Jersey....however, the interesting part is that they sent them to Stroud in Oklahoma City for the re-cert. Stroud shipped them direct to me.
If you go another route, it wouldn't hurt to check with them, and they were quick.
http://www.stroudsafety.com/RestraintSystems.html
Clark