It appears the virgin have not anticipated the level of interest in upgrading to the new V6 box and have unfortunately not updated the information on the page and have instead removed it. Poor customer relations, springs to mind, the only realistic way to get hold of a V6 box is to use the 150 number from a virgin mobile or landline and navigate to retentions, (220.127.116.11.5). You may be able to get a deal, opt for the self install, it is fairly straight forward and requires no real technical ability, just read and follow the instructions in the supplied booklet.
You can't learn anything from a mistake until you admit that you've made it.
They haven't removed the information from the page at all. The problem is the link takes you through My Virgin Media, which doesn't work for a lot of customers so therefore they won't be able to order the V6 using this method. But do ring Retentions as suggested and they should be able to process the order. Make sure you don't pay anything, there are no charges whatsoever, anyone who tells you different is lying.
Also, the message is misleading as it implies imminent withdrawal of the affected boxes and this is not the case. You are good for at least another 6 months if you'd prefer to wait. When they actually start the forced withdrawals, you'll get a letter in the post giving you lengthy notice, and the order process will be simpler as you'll just fill in a form on the website and then someone will ring you to book delivery.