Asus 6z (India version of Zenphone 6) comes with pre-installed Facebook Messenger. I don't use Facebook so I uninstalled messenger but today I saw, there is app named Facebook Services not visible in App drawer, used 1% battery and active for whole time since full charge. It transferred total 485Kb data, I guess it's total since I used my phone, 30 days.
I am being paranoid or the "Evil" Facebook using my data even though I am not using Facebook.
Question to Asus: You have give such near stock android experience why included Facebook Trojan in our phone which can't be uninstalled.
There is another hidden Facebook app which you can see in App list in setting.