I am having the exact same problem at the moment with giganews.
My web browsing experience considering i am on 50mb is pathetic, download speeds over any protocol including http is crap but newsgroups usually over port 443 (ssl) were fine and even that sucks now.
This just isnt acceptable considering how much money i pay them for this ***** service, but dont worry any speedtest sites you go on tell you its fine
VM are full of **** and i'm sick to death of the constant nonsense with their service in this area. ill be cancelling when i get home tomorrow, i already have a BT phone socket in the house so looks like ADSL it is.