We have used Eclipse for the last 3 years or so with no problems. It's extremely reliable and has no cap. It's easy to get through to Customer Service and Tech Desk and both depts are very helpful. Eclipse has won many awards for being one of the best ISPs around.

It's not the cheapest but IMO it's defo one of the best.

http://www.eclipse.net.uk/index.cfm?id=bbhome