First need to check how you are testing the speeds. Wifi or Ethernet? What devices? What sites?
Can you see this protocol I have posted before _______________________________________
If you think that you have a BB speed problem, then to check the speeds coming in to your Hub properly, and whether they match what you should be getting, you cannot rely on wifi tests, - no BB supplier guarantees those - only speeds "TO" the Hub are guaranteed.
So, can you test speeds directly like this. As you expect >100Mbps then connect a 1GB enabled computer/laptop, with up to date drivers, via a NEW and working Cat5e (or better) ethernet cable, directly to the Hub which you have put into “modem mode” (https://www.virginmedia.com/help/virgin-media-hub-modem-mode ) so no other devices can be connected on ethernet
If they are still low – boot you device into windows safe+networking mode to disable any potentially interfering software - and try again.
There are many posts on here where QoS software, unknown/flaky software, old network card drivers, corrupted browsers, bad cables or other connected devices are limiting speeds on tests.
Report back what that gets.
-------------------- John --------------------
I do not work for VM. My services: HD TV on VIP (+ Sky Sports & Movies & BT sport), x3 V6 boxes (1 wired 2 WiFi,) SH2 in modem mode with Airport Extreme Router +2 Airport Express's. On VIVID200, Talk Anytime Phone, x2 Mobile SIM only iPhones.
I Don't know where you are located, but in both Croydon and Crawler (see other posts), there seem to be speed issues. Numerous customers have posted about this, but VM has not acknowledged it yet, at the time of this posting.
I'm personally only getting 4 Mbps, according to speedtest.net , whilst i should be getting 500 Mbps. Which the test showed a week ago.