Handling time Gap issue with Amazon

The issue is as follows. We sell items in 3 tiers of delivery times. FBA , FBM Prime(1 day handling), and Normal FBM (7-10 day handling time). Sometimes we sell the same product in all three methods, though each has its own separate sku with a timer identifier in it. We have 3 warehouses, 1 in FL, 1 in Michigan , 1 in Canada. Our products are often moving between warehouses (in the same way that FBA redistributes products across its centers for faster delivery options).

 This Warehouse transfer of products that is going on at all times is why we have 7-10 day handling time set manually for our "FBM" non prime listings. We almost always exceed expectations here, and often will have the item at the closest warehouse already there, and not in transfer. So we send it out immediately and while the customer was expecting it to take 2 weeks to get, they get it in 3 days. Under promise/Over Deliver. Time honored. Heres the problem. Amazon somewhat recently created a new system called Handling time Gap. Which is the difference between your stated handling time, and the historical average of your actual handling times. And have overridden our manual handling times on products without our consent because we have been outperforming those handling times, leading to us inevitably having actual issues with shipping on time because of products moving through our pipeline of warehouses. This is making our On time delivery/shipping metrics take a hit. But its not our fault, we have the option AHT turned OFF, but Amazon is still altering our handling times on about 20-25% of our FBM listings. Every time we talk to an agent they want us to turn that option on (NO way) and then file for exemptions on each of our listings (we have thousands). This is not feasible, nor do I trust for a moment that wont cause catastrophic issues. How can we get Amazon to STOP messing with our manually set handling times on these listings?