Inexplainable 12,4GB internet usage spikes.

I live in a dormitory with an Internet usage limit of 80GB per month. Not only is it little, 4 months ago my internet suddenly just went away, because nearly everytime my PC is on it's downloading 12,4GB (always excatly this amount) of data.
I don't no where from, neither where to, but it's just gone from my data plan.
Our provider says it's not their fault, so I'm trying to fix it on my own for a long time now.

Anybody an idea what is happening?

I already set my PC in Wi-Fi to "metered connection" although I'm using LAN.
I already turned off the peer to peer in the update settings.
I already defered updates. (not sure yet if it's working or not)

Thanks in advance :)

Edit: Speccy: http://ift.tt/2C4cGhi

Submitted January 01, 2018 at 08:59AM by schmaul http://ift.tt/2CrbO9C