Been using Plusnet since my exchange was broadband enabled about six years ago. Never had a problem and despite my exchange not being unbundled, an acceptible speed: up to 8 Mb/sec claimed, max achieved about 5 Mb/sec. They also host my websites as part of the service with 100 Mb storage on their servers and I get unlimited e-mail addresses, ending plus.com
British call centre for help service - bit difficult to find the telephone number on their website - but it is there. Engineers at the other end are helpful.
P.P.