Phal in Dire Need of Help (or is it too late?)

[Phyrex]

Hi All,

I know it's only my first post but I am in dire need of help with my Phal.

It had 8 flowers (3 still unopened) when I bought it in May of this year. I've been watering it once in 2 weeks until the flowers started to drop from the bottom upwards. I've been searching for answers and someone told me to cut the flowers of just above the last notch so that a new spike would grow. I did so but, concurrent with the flowers falling off two of the bottom leaves turned yellow (again a bad sign). Now the third (of 5) has turned yellow also. The potting material keeps water for a very long time and I was worried about some of the roots being bad so I decided to clean up the pot and try to repot it before it is to late. What I saw horrified me. The whole stem is black and it only has about 3 semi healthy roots. Please see the pictures and tell me what I can do to save my once beautiful plant?? Help..

Sincerely,
Phyrex