I think Halo 3 was introduced by BT purely as a marketing exercise to allow them to claim, untruthfully, that existing customers will never pay more than new ones. As has been said, that is true ONLY if a new customer is stupid enough to sign up for a Halo 3 deal.
A monthly price of UKP50 to 60 is quite normal for Halo 3 without any TV service at all. New customers get deals at around half this price, albeit without the Halo 3 bells & whistles which are pretty much worthless.
As has also been said BT make it almost impossible for a Halo 3 customer to downgrade to a half price non Halo deal.
These marketing tactics seem to me to be more appropriate for a street market trader than a supposedly respectable broadband & telephone provider
