Go Zen - never had a single problem with these guys - you get right through to tech support / customer services and there always willing to help out.
The can be a bit pricer than others though - but hey - works paying
Saying that though - Metronet @ 20:1 contention on 2mb is 27.99 (ex VAT probably) and its capped at 15 gig - in that you start paying per meg after you use up your "allowance"
Pfff...