When my Galaxy S6 updated to Nougat software, I lost fast charging capability

Recently, My At&T Samsung Galaxy S6 updated its software to the new Nougat 7.0 version. However, Since the update, I can no longer fast charge my phone.

I have the proper Samsung Adaptive Fast Charging Wall Charger that I purchased from YOUR AT&T store. (You charged me $39.99, I might add, when it is available directly from Samsung for only $12.52). The Fast Charging worked perfectly until the 7.0 Nougat update. Yes, I have also wasted another $56.00 buying the Wireless charger, as well, to make sure that it was not a Faulty USB port issue. I have also plugged my Samsung Adaptive Fast Charging Wall Charger into multiple other Galaxy S6 phones, that have NOT updated to Nougat 7.0, and are still running on the 6.0 software, and the fast charging works Perfectly with my cord. Obviously, this is a software issue as many thousands of customers are experiencing the same problem after the software update. Can you please  tell me what steps I can take to possibly downgrade my software version BACK to the 6.0 version as I am in Desperate need of the Fast Charging capability.

Thank you for your time and consideration with this matter.