I've been on Plusnet (fibre) since February and had no problems with anything.
Some people say Plusnet phone/ticket support is fine, some have trouble with it. I had one or two iffy things after ordering and before connection and the phone people were OK.
The Plusnet reps who are here most days, and every day I think on their Community Forum, are excellent.
That said, I don't monitor the Zen forum here, but we don't get posts in "General" or "Unhappiness" about them. You will see a lot of posts here from one individual rubbishing Plusnet, (he changed nick a few months ago so it might look like two, but one stops and the other starts so no deception by him in that respect), but every ISP gets the occasional highly disgruntled individual. There have been a few with Zen in the past, and it's nothing to worry about with either of these ISPs.
The Plusnet speed limiting at certain times of day is now far less significant. See this page
My broadband basic info/help site - www.robertos.me.uk
Domains,website and mail hosting - Tsohost
. Connection - Plusnet
Extra Fibre (FTTC). Sync ~ 56.0/13.9Mbps @ 600m.
"Where talent is a dwarf, self-esteem is a giant."
- Jean-Antoine Petit-Senn.
Allergy information: This post was manufactured in an environment where nuts are present. It may include traces of understatement, litotes and humour.