"will have to seriously consider leaving I think".
In fact you don't have to leave Virgin Media. Just stop using their email and switch to using a better independent email service. I have been a customer of VM since before they were VM and have always been very happy with their broadband and tv services. However, t I have never used their email service.
There are many free email services that you could move over to. See here for a review of the best https://www.lifewire.com/best-free-email-accounts
In truth the Virgin Media email service is a very basic one that does not seem to be high on VM's list of priorities. That's no surprise because they are first and foremost a cable internet and tv company not an email provider.
Switching to another email service such as Gmail will not only give you a more reliable, more secure and better supported email account but you will be able to carry on using it with any Internet Service Provider you use in the future.
Just as a side note. You are probably aware that "Virgin Media" has now become "Virgin Media O2" . Their new partner, O2, used to offer free email accounts to all O2 customers but closed them all down back in 2013 and no longer provides an email service. I sometimes wonder whether VM regret not taking that step with their email service.
I'm a Very Insightful Person, I'm here to share knowledge, I don't work for Virgin Media. Learn more
Have I helped? Click Mark as Helpful Answer or use Kudos to say thanks