Yes, indeed, for some reason you had to opt-in to the last round of upgrades. Sounds like they'll be doing the same this time as well.
As an area of the network is upgraded we will write to all of our customers in that area letting them know that their upgrade is ready and all they need to do to accept the upgrade is log on to their account online to confirm and we will then increase their speed. By writing to them we are not forcing the upgrade upon them and if they want to stay as they are they can.
Why anybody would refuse the upgrade I'm not clear on! It's not like they'll reduce your bill if you do. It'll reduce VM's own bills though, for sure.