Here is the reply from a VM tech rep I was talking about, specifically in reply to someone asking about the 2 free months
Hi Mr
If you upgraded to XL package or any digital packager then you need to have
this for 30 days you can then down grade if you decided it wasn't for you.
You would need to speak to customer care to upgrade your package.
Hope this helps
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Kind Regards
Virgin Media Technical Support
http://status2.virginmedia.com/