Preferential bidding?
You mean a classic North American airline style system . . . the kind where the most junior pilots dine on a steady diet of table scraps, stand-by and the !!!!iest trips while the senior guys suck the sweetest nectar?
I can understand there are grievances with some of the rostering decisions, but I feel it is a fairer system, with more people sharing the load of the bad trips and reaping the more sought after ones. It has been my experience that the rostering department does entertain requests.