They do not advertise XL Broadband at 30mb. They advertise XL broadband at 20mb. Existing customers signed up for XL broadband at 20mb. They're getting a free upload upgrade as it is. They did not sign up for XL broadband at 30mb. Actually if you look at their online shop you'll see what they advertise is 10mb, 20mb, 50mb and 100mb. You bought 20mb, you might be getting 30mb or you might be stuck on the 20mb you signed a contract for. Deal with it.
http://shop.virginmedia.com/home.html
People who signed a contract for 20mb service will continue to get 20mb service (and a free upstream upgrade). If you think there's a problem getting what you signed up for perhaps you're the one taking the p***
Next thing you'll be whining you don't get free 50mb when you pay for 20mb. Or your 2003 model car doesn't get a free upgrade to the 2011 model but new customers do.