Seems depending on what you read on the Plusnet site, you get a different answer.
IT USED to be the case that your connection speeds were slowed down until the month end. And there are still documents on the Plusnet site that state this.
However now it seems they just start taking money, and it's upto to you to set a limit as to when to stop..
https://portal.plus.net/data_transfer_watch/And when you hit the limit of money, (and I quote)..
If your broadband charges (subscription plus additional usage) reach your Maximum Broadband Price, you'll be disconnected from the Internet. You can either wait until your next bill, or increase your Maximum Broadband Price, to immediately benefit from additional usage.When did this policy change occur? Was it widely publicised?
