I just called support, telling them that 3mb/s upload speed is 12 times lower than the GUARANTEED upload speed and he says that there's nothing wrong with the internet... What am I even paying for, I'm already 40 minutes on the phone
What is the make/model of the PC/laptop? Some have been known to have software installed which hampers internet speeds. Dell commonly do this but there are others too. If using speedtest.net sometimes the amount of animnated adverts on that website can use up 100% CPU and cause poor speeds on older systems, a simple ad-free test you could try is www.fast.com
Your actual internet connection looks fine from the stats posted earlier so it's really just a case of trying to work out what is causing the slow speeds.
If you have a good phone/tablet (iPhone/Samsung Galaxy etc) try a WiFI speed test on those (using the 5Ghz network).