When you say your IP address is blacklisted, do you mean that it is on the spamhaus blocklist SBL/CSS? You can check that here: https://www.spamhaus.org/lookup/ If so, it is not Virgin Media's responsibility to clear the snowshoe spambots off your network.
In the meantime, you should be able to send if you use webmail. To use an email client, try using a data connection instead of your home broadband, or if you go away from your home broadband - at work or public wifi. But don't delay finding the spambot - who knows what other malware has been installed on your network!
Come back here if you need assistance - we want to help.