I am in a situation where I am still being billed by Plusnet for my BB despite leaving in August and despite paying the final bill. I contacted Plusnet to ask what was the final a mount I owed, I settled this (it was low as I pay line rental saver upfront). Paid the amount I was asked then I get a text and email to say I have outstanding amounts to pay. I speak to customer service and they assure me it's just the new billing system and I don't owe anything. a few weeks later they take money from my bank account. I have just spent 20 mins on hold and managed to speak to someone and process a refund which will take 21 days via cheque.
I have had this on the mobile side of plusnet after leaving I was being billed for a mobile number that had been transferred over to vodafone for months.
Plusnet really need to get their billing sorted. To be fair, I never had any problems whilst with them but once you migrate out they just can't seem to get a grip on closing accounts.
It's a pity because I don't think I will go back to Plusnet because of this.