Phone doesn't turn wifi off and weirdly transmits data
I've followed Izzi's advice and it worked. Here's what i did:

I used the firewall app, afwall+ ,turned it on( and used whitelist - blocking everything ) , turned logging on. 

made phone sleep. 

Than turned it on - and on the firewall log - i've seen the sources of traffic - all pointing to google, which i can live with - so i didn't continue further.