i am juts trying to help. Normaly i think support must help you. You paid them. They can remote control your pc with teamviewer and try something. you are not the only one with that problem so they must know something about problem.
and dont use antivirus realy windows have antivirus build in and is same but more efficienc and dont choke your pc with scans and updates is perfectly gut for normal use. you are just slowing down your computer