Have they considered autoimmune inner ear disease (AIED)?
http://www.dizziness-and-balance.com/disorders/autoimmune/aied.html
Ninety percent of cases of sudden hearing loss remain unsolved as to cause--they can only speculate or make educated guesses. But usually it's one-sided. Since you have progressed to the other side, Meniere's or AIED would be considered, among other things presumably.
See a NEURO-OTOLOGIST (ENT specializing in the inner ear) if you haven't already. See lists at the American Neurotology Society Web site.
Good luck--what a bummer. I have hearing loss in one ear only.
Nancy T.
Vertigo with loss of hearing can be of 'central' causes or 'peripheral' or 'vestibular' causes. The attempt might have been to rule out the serious central causes.
The vestibular causes affecting hearing and 'balance' can be a labyrinthitis, Menierre's disease etc. Steroids was given as salvage.
Hope you are not a hypertensive. How is your blood urea and sugar levels? Do you have any other medical condition? Are you on any medication for long periods now?
Best,
Thomas Antony