I`m sorry I don`t understand what the problem is, all the loco airlines change fares based on the loads, the better the load the higher the fare that`s how they make their money.
Look at Easyjet or Ryanair they may advertise a fare of say £15 but as soon as the allocation goes the fares go up in stages and perhaps a couple of days before departure the fare maybe £150
£12.50 cross the Irish sea sound pretty good to me.
Golf India Bravo