I feel your pain mate, i've been through the same problem with my gt30'd T4.
The actual oil inlet into the turbo itself is an M11 thread but the other female is normally a .4, i ended up making up my own brass sleeve and bolting on one of the fittings for a tenner you can get off the bay.
If you need a shorter hose let me know, i've got a few i don't need, thanks to idiot suppliers who give the wrong size hoses...