A Tiscali engineer informed me on the phone in December that my line (580 yards from a fully equipped and upgraded exchange, including ADSL Max now) would not support 2MB.
As I had been receiving an exemplary 2MB service from Tiscali for around six months before it undertook "service enhancements", I told him he had shot himself in the foot.
But he wouldn't budge and I ended up with 1MB.
That's why, coupled with one or two other minor problems, I'm switching to the TalkTalk offer after eight years with Tiscali (earlier WorldOnline).
By the way, I know the full history of my telephone exchange (one of two serving the town) because one of my mates used to be the exchange manager..:-)