Need help with Medicare

I have medicare and they cover weight loss surgery and have no 6 month supervised weight loss diet. But the company that administers medicare for the state of Kentucky on my last medicare summary notice , was CGS and they require the 6 months supervised diet. But today i got another medicare summary notice and the administrator is National Government Services. I thought maybe this new paper was for part A or something but no. They are both for Part B services, in which i was told Bariatric is covered under. But the thing is i cant find anything about requirements on their website. Can someone please help me out!!!!