Please help -Oncidium root rot!

[Sahlabiya]

Hi Again,

I keep writing about this Oncidium - it keeps taking new turns for the worse . I had taken it in to the nursery where I bought it when I first caught that it had root rot. They helped me repot it, put it in ban-rot and repotted it in a media with fine bark, shredded New Zealand Sphagnum, small pumice. Since then no new green growth has occurred, and I keep finding more rotten things. I pulled off a brown pseudo-bulb this morning, took it out of the pot and of course found more root-rot. I have only watered it once a week since I had it re-potted. I tried to email the nursery again but they did not answer this time.

I did my best to take out the rotten roots but it is so hard to find them in the whole tangle of roots! At the moment I have it in water with fungicide (Agri-Fos) and I plan to let the roots dry for the rest of the day. I am wondering what I should use for media that will give it the best chance for life? The media was quite damp when I pulled it out and I last watered four days ago.
Any help would be much appreciated - I really hope to save this orchid!!