The official PlusNet forums are the logical place to post.
There are still plenty of complaints, but I see the company actually doing something to solve them.
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As was the case here, the PN reps pick off the ticket-type complaints and do something about them. That's good PR rather than good CS because up to 95% of complainants never find their way to the forums.

If 95% of complainants never find their way to forums, then why do you think this is the best place to conduct your anti plusnet campaign?? Surely there would be better avenues for you to follow in order to take plusnet to task?