As usual the moaning on Pprune but I doubt anyone has put in any formal complaint which would require an explanation.
Simply put, someone in the top bid group who was disadvantaged should take it through whatever formal grievance channels the company has and demand explanation. This will elicit a formal reply and from this reply the matter can be escallated again. I.e. If there has been a policy change it should be promulgated and if the system is being deliberately corrupted for no good reason, the culprit should be brought forward for explanation.
Anyone who has been here for an appreciable amount of time should know that writing emails, making phone calls etc. is a complete waste of time. The matter will be passed around until everyone gets bored or something else distracts them. Standard management technique.
Pprune is a great forum for raising awareness and sharing viewpoints but as a method for challenging the system it is largely ineffective. Hence the pilots generally have a good moan and then get steamrolled.