Why can't you use denoising on a render farm? It should be possible.
Increasing GIvsAA should help clean up noise in glossy reflections and refractions faster. Just don't go too high. I would check with 32, and 64 as a last resort.
By the way, I do not know what your scene looks like, but maybe you can get away with some other properties than glossy refraction? Have you tried using translucency instead?