I agree that you need to get your plant out of the moss. It's probably tightly packed so even though you only watered it once a week it probably wasn't getting the chance to dry out leading to the loss of roots.
What you repot into will depend on your growing enviroment and how much you like to fuss over your plants. Bark or moss isn't for everyone.
If you decide bark is the way you want to go be sure you soak it overnight before using. Then, once you've repotted wait several days before you water again. This gives the roots a chance to heal.
Using a skewer in the pot will help you know just when to water. Place skewer in pot for about an hour, remove and then check for moisture. If it comes out wet or damp, you'll need to wait to water. You can also use this method if you decide to replant into moss or even a combo of bark/moss.
Additional info on your growing area such as light, humidity etc might be helpful in advising you further.
This is a great thread to read especially if your new to growing, worth the read even if your not.
The Phal abuse ends here.
Judi