If you've *never* received anything above your original 4Mb then in your position, I'd check the config page of your modem to make sure that it's got a 20Mb profile.
If it's not still stuck on 4Mb, then it'll be worth checking to see if your modem is actually capable of handling 20Mb -- lots of the older models can't.
And if that doesn't lead to a solution to your problem, then you'll need to help Tech Support to diagnose the cause -- I'd suggest that the easiest way to do this is via their dedicated newsgroup, virginmedia.support.broadband.cable, rather than the phone lines or even email.
But before you dive straight in, TS will be after a range of information from your connection -- do the checks first and paste the results into a message. (TS expect to reply to every post within 4hrs but you'll normally get a response within 10 minutes.)
First off, connect your pc straight to your cable modem, by-passing any router.
Then collect the following information (from Annie's excellent
Broadband FAQ):
* Your netstat -a (see
Q05 )
* Your total download speed from 4 simultaneous file downloads (as outlined in
Q02)
* Ping to
www.bbc.co.uk (see
Q06)
* Two trace routes to
www.bbc.co.uk (see
Q06)
* Your modem logs and signal levels (see
Q07)
* And a good description of your exact issue
* Your alias - The part of your email address before the @ symbol, this is so support can identify your account details on their system. ie. if your email is
fredbloggs@blueyonder.co.uk or
fredbloggs@ntlworld.com then fredbloggs is what is required
If you've not already setup access to newsgroups, you'll find
a guide here.
And VM's Tech Support group is 'virginmedia.support.broadband.cable' on news.virginmedia.com or text.news.virginmedia.com.
hth