They are making changes which include charging if you want to choose economy seats before a certain date but from the web site for PE, this is not applicable ie:-
Advanced seat assignment
Published 21/11/2013 02.44 PM | Updated 31/12/2013 10.37 AM
Will I need to pay to choose my seats in advance?
• If you are in Upper Class, Premium Economy or Economy booked in Y Class you can choose your seat free of charge any time from making your booking.
When you ask them about it they just ignore this statement and say that no-one can choose seats before 1st June. They also ignore the following and say that it is wrong:-
Selecting Seats and Exceptions
Published 17/12/2007 03.01 PM | Updated 23/12/2013 02.19 PM
If you already have a booking to fly in April seats can be assigned up to 30 days before departure. For flights departing and booked after 1 April seats can be chosen free of charge on booking or up to 336 days in advance.
It is difficult to see what their policy is.