"Prices changes - 2nd September 2015

New pricing will apply from 2nd September 2015 as set out below

Line rental will increase from £15.95 per month or £15.99 per month to £16.99 per month
Line Rental Saver will increase from £155.88 for 12 months to £185.88 for 12 months (for those customers signing up or renewing Line Rental Saver from 2nd September)
Evening and Weekends will increase from £2.00 per month to £3.00 per month
Anytime with and without 25% off international destinations will increase from £5.00 per month to £6.00 per month
Anytime International 300 will increase from £7.00 per month to £7.50 per month
Our call set up fee will increase from 15p to 16p per call
Geographic calls to 01, 02 and 03 numbers will increase to 10p per minute and mobile calls to 13p per minute
Postage & Packaging will increase from £5.99 to £6.99 (excluding YouView+ set top box at £7.99)
Our early termination charges will change. How much depends on your package.
Some of our call rates will change"

http://www.plus.net/info2/legal/price_guide.html

Normally they increase prices yearly beginning of Oct. Late Sept last year. To get extra money off customers quicker  i presume they have decided to bring it forward to 1st of Sept 2015.

Although i see no mention of it,  as the increases will be a change to customers' terms and conditions, you should be able to leave penalty-free.

To do this, you normally  need to tell Plusnet within 30 days of it telling you about the price rises. Plusnet should then cancel your service within 14 days.

Alas - Plusnet appears to be going down the pan, as far as competitiveness is concerned.  I guess their owner, BT, is squeezing them for more revenue to fund the outrageous prices they have paid for sport - most recently for the Champion's league, where they outbid ITV if my memory serves me correctly.  I fear we will not be Plusnet customers for much longer as there are now much better deals available. 
This continues the inexorable rise in fixed line rental. In 2006, when Ofcom removed the cap on line rental, BT charged just £11.50/month. Ofcom claimed there was now sufficient competition they could remove the cap. Result - a  48% increase in line rental. Well done to the great non-regulator, Ofcom.  Who do they really represent?  Doesn't seem to be the public.