Why has Qantas stopped using B744's to the Anartica

Can anyone update me to why Qantas is stopping it’s B744 fights on New Years eve to the Anartica?. I have read this a while back, So what is wrong with these aircraft or is Allan Joyce going to use A330’s or A388’S

A brief check of this has found that flight OPS have scheduled new years eve flights this year and 2016. VH-OJS VH-OJU one of them will be flying down there back there in down under