I suppose the point is that VM employees here that are telling us that the speeds won't increase have no incentive to do so whereas the ones that are speaking to people on the phone are likely to be trying to retain or gain subscriptions.
Having said that, I've just got off the phone to CS about adding V+ to my existing subscriptions and switching to the 3 for £30 package in the process. I am currently on Broadband L package but was prepared to go down to the Broadband M package (which is what you get for the 3 for £30 deal) as I'm not a big downloader. I queried whether the M package was going to be upgraded next month and was told that it was only the XL that would change. In the end I stayed on L anyway as the total price for my new package including V+ was the same as I'm paying now without it.