Nursery is now open 52wks and charging for all sessions

Hi
Does anyone know where I stand with the following?
My daughter has been going to the same nursery for the last 3 years and they have only ever been open for 51wks (closed the week between Christmas and New Year, so we don't pay for this week). They turned round on Friday and told us they were opening the Christmas week and today informed me that I would need to pay for these session even if we don't use them. Can they do this? They claim that it is what parents want - but we haven't been consulted despite being full time and the information we got when we started stated 51 wks (I'm sure all the other parents would of been given the same info). They have also started a Christmas Club this year, more sessions you use the more you will save in December, just seems a bit convent 6 months after starting this club they have now decided to open for 52wks. OBTW - we don't get any weeks off for holidays, only days we don't pay for are Bank Holidays and weekends (were open for Jubliee and the Royal Wedding extras)