Where can you buy Fast Track coupon for Suvarnabhumi

I came in on business class yesterday with a Fast Lane voucher and entered through the archway. The lines to the Immigration desks were 10-15 deep, packed with many (Chinese and Indian tourists - no racism intended), the former who were clearly part of a group tour with a leader waving a flag and shouting rather loudly. They seemed to proceed rather easily to the Immigration desks without being asked for their (illusory) Fast Lane card. As the two channels have cut-through from normal Immigration counters, the separate entrance to the Fast Lane section is pointless, as in the whole concept, if Immigration does not enforce qualification. "Fast Lane" obviously needs to be in Chinese and other languages too. There were a number of other Fast Lane voucher holders obviously annoyed at the poor management of the system and they let their views be known. But as I have long learned here, there's no point in discussing it with someone without any authority. It would however be nice if they could tighten it up.