I had my son's E46 window repaired at P.G.Glass as they normally replace car glass for insurance purposes. I got the regulator or whatever it is called (the part with the cables and channels) from Robs Motor Spares in Somerset West but i know that Masterparts and Goldwagen also stock it, so phone around for the best prices. I am not sure if they carry 5 series stock as well but try them. They charged me R350 to do the work which i thought was a bargain. Parts was about R800