I am in the same boat as you and really frustrated by it. As I see it, WDW has set it up with the dining plan so that you have to book several months in advance to get ADRs or you are going to be S.O.L. on eating. However, by doing this, we end up booking the resorts and they are full enough by the time the codes open up. We have gone every year and stayed in a deluxe for the past few years and I can tell you that I had no problem applying the code then so I think the other thing that has happened is that Disney has become a victim of its own success and is being much more restrictive on what the codes can apply to.
Yesterday I was on the phone for an hour (as the case always seems to be), for the 4th day in a row being told exactly the same thing, and at the end the CM says, "keep calling because you never know" at which point I admit, I lost it. I am paying for a top level resort and have visited annually, so by any measure am in their most valuable customer category, yet I should have to waste an hour every day to be treated well?!?
I have an alternative solution, next year I will take my wife and kids to Beaches or some other non-Disney resort that may actually appreciate us coming.