Why Google Play services upload nonstop 1MB/s everytime the device is connected to wi-fi?
I think you are infected  with a malware that spy on your phone and upload to a comand and control server almost everything from your phone like: pictures, sms, whatsapp conversatin, facebook converstion, viber conversation etc, and to not affect your mobile data plan it starts the comunication with the server whenever you are connected to a wifi network...
Im not a pro on android but I've done it before and I already know what happens behind, how it works and how it affects your phone.
Do a backup but dont backup apps and after it try a factory reset.
Install the list of apps u had from Play store again 
(Its better to backup only pictures/videos and contacts and nothing more)
I hope it helps u.