Out of curiousity why does Plusnet feel that those of us on Premier need to be subjected to both a SUP and traffic shaping? Especially as many of us will still be paying the old price for what is now a much reduced service.
Secondly why drop the price of the service wouldn't it have made sense to keep the pricing the same? It makes little sense to cut prices and then bitch about bandwidth usage / costs. If you have bandwidth issues then surely a slight price increase would be better than a price decrease?
Why not just go with the older FUP with a usage limit and remove traffic shaping from Premier accounts - this would still allow you to control leechers as they would still need to comply with the x amount peak time / x amount off-peak allowances.
The route you have taken is to literally punish everyone who is on premier accounts regardless of whether they have ever broken the SUP / FUP allowances.