I recently downgraded from Unlimited Fibre Extra to Unlimited Fibre (21-02-2020).
Contract is for £21/month inc £19.99 line rental for 18 months, so Unlimited Fibre is £1.01/month. I have paid line rental in advance and am still being charged £15.99/month for Fibre.
Overcharged on both March and April 2020 bills.
Plusnet not taking calls or live chat. Continual billing problems with Plusnet, a complete joke!!