Your problem...
...in common with a LOT of other people, is that YOU FAIL to read the T&Cs. I'm not trying to be a smart-arse about this but YOU gave them permission to make changes to the services they, or others on their behalf, provide after you signed on the dotted line AND give your information to third parties in the course of providing those services.
Also, to be fair to Virgin they DID give notice on their website, and send out an emails to the same effect, that they were switching to Google as their email provider rather than continue running their own in-house services inherited from Blue Yonder, NTL, etc.
The following is from: http://shop.virginmedia.com/the-legal-stuff.html
B (1): General
f. Some parts of the services (for example, television channels that form part of our television services and other content on, or accessible via, our television services) are supplied by other organisations. As a result, due to matters outside our reasonable control or for commercial or contractual reasons, Virgin Media Ltd may change, cancel or postpone all or any component part(s) of the services without notice, but giving you reasonable notice of any withdrawals and changes where it is possible to do so. You will be entitled to end these agreements if the changes are significant, as described in paragraph J5.
G (2): By having the services provided by us installed in your home and/or by using them you are providing your consent to use your personal information together with other information for the following purposes:
a. providing you with the services, service information and updates;
Occasionally third parties may be used to process your personal information in the ways outlined above. These third parties are permitted to use the data only in accordance with Virgin Media Ltd's instructions (as applicable).
H (2): Virgin Media Ltd and/or Virgin Media Payments may at any time improve, modify, amend or alter the terms of these agreements and/or the services and their content if:
b. Virgin Media Ltd decide that the services should be altered for reasons of quality of service or otherwise for the benefit of customers or, in Virgin Media Ltd's reasonable opinion, it is necessary to do so;
c. for security, technical or operational reasons;
f. if the changes or additions are minor and do not affect you significantly or we wish to have all our customers on the same terms and conditions; or
g. in all other events, where we reasonably determine that any modification to the relevant system or change in trading, operating or business practices or policies is necessary to maintain or improve the services provided to you.