Bobdn: Holy crap, I did download an episode of Made in Chelsea.
That sounds like a pretty serious fault, I'd get it checked out immediately.
Oddly, my VDSL connection rate went from 52Mbps down to 40Mbps and has gone from DLM 1 to DLM 2. Guess there's a borderline cable somewhere between me and the cabinet (which as it turns out must be a long way away, as I can't find one within several streets of me.)
Actual peak download speeds have also dropped from around 3-3.5MB/sec to 1.5-2MB/sec. Upstream is still 10x what ADSL was so not too worried though.