Looking at your bills the extra £3 is very definitely a Tivo fee rather than a general increase come early. If you were told that this wouldn't apply to you then you should ring up, but I thought the Tivo sub became per box rather than per account some time ago? Perhaps Ben et al can confirm?
---------- Post added at 14:25 ---------- Previous post was at 14:24 ----------
And in fact he's beaten me to it