Topiary Cube dying

Hi there, I bought a couple of these cubes about 2 month ago and they look like they are dying is there anyway I can save them? I've attached a photo to show what I mean

 

Looks like box blight.
Ive got this too. What I do is remove the dead leaves and bin them,spray with mixture of fungicide,aspirin,seaweed and a drop of fairy liquid.
The damaged stems regrow next spring. This doesnt cure it but manages it for me.

 

Thanks Tam, Just a bit anxious about cutting a large hole in the middle of the cube, I think most of it will need to be removed. They cost me £60 each but think I'll just need to go for it

 

Most of the time i dont cut back the stems, just removed the fallen leaves and shake the plant to get the others off too,then binned.
The seaweed really seems to help them out. I dont prune when humid or damp and only shape them in October now because the blight is still in the plant but under control ish .

Btw check for box caterpillars too, maybe not blight ?