In reply to captain paranoia:
> Plusnet is owned by BT. Which is odd, since they seem quite a bit cheaper than BT... Horizontal market differentiation?
It's not at all odd if you understand how BT works. As an ISP you buy your lines from BT Wholesale, they have to give everyone (including BT Group companies, which Plusnet is part of (as is BT Retail)) the same price. Obviously if as an ISP you buy in bulk you could probably negotiate a discount. I suspect Plusnet are cheaper because their overheads are cheaper than BT Retails.
When you get broadband from 'BT' you're buying it from BT Retail (which iirc has a 'Consumer' and a 'Business' arm now as well).
Due to monopoly issues BT Group is a very segregated organisation.
It's well known in ISP circles that BT are often the expensive option for connectivity.