I have successfully changed one of my two V+ boxes to Tivo, which I was told was essential. They only sent one, and I was informed that I would be called in the next day or two about the other. This hasn't happened, it's three weeks ago now. So I phoned and was told I can't arrange to get my other box over the phone. The girl said I would be contacted by email.
I asked why they didn't do the two at once. "I don't know". I told her I was willing to bet I would not be contacted again and would be stuck with an obsolete box.