Tiscali advertise their service as unlimited and its them I'm with. But in common with most BB suppliers their definition of unlimited is reasonable useage. If you download huge amounts then you will get a warning from them, if you ignore the warning and continue you will get cut off.
I am happy with my connection but because of their pathetic customer service I would not recommend them.
I cannot suggest anyone in particular for your new provider but would suggest you don't consider Tiscali for the reasons I have stated and I'm only on the lowely 2 mb connection it does me fine I don't need more but I don't know what their faster speeds are like.