Leaders define the culture of the organizations they lead through their actions and their policies. You've clearly created a culture which makes it OK, or even encouraged, for your employees to screw your consultants to enrich you and themselves. But, at least in my case, you've probably already lost more business than you made in margin by screwing me on my rate. Think hard about the impacts of your business decisions.
I worked normal hours but I was not allowed to work overtime. They promised time and one-half for overtime but then they wouldnt let me work OT unless I was paid straight time. Bait n switch.
• Strip commission from any recruiter who baits and switches a candidate on rate, in addition to given them a written warning that if they do it one more time, the result will be termination of their employment;
• Drop the rate penalty from your employment contract and just make it a straight fee election;
• Drop the language in your contract about your compensation rates being a "trade secret" - if you didn't screw your people, they wouldn't be tempted to complain;
• Drop the automated email system
• Communicate more proactively with your consultants so they know what your process is, what to expect and when, and allow them to opt out if they don't care.