Sorry you are having so much trouble. Perhaps you could obtain paperwork from one of the plumbers that said the shower could be installed and go back and present it to the bureaucratic idiots. Ask (politely) to speak with a supervisor, and explain that while installing a shower is in fact a viable option, moving is not a practical option for someone with your health in its present state. See if there is a social worker or counselor in your area that could advocate on your behalf. Also try contacting the Legal Aid office in your city. You might get some assistance there.
I hope you get this worked out soon. Wishing you well,
Life is measured not by the breaths we take, but by the moments that take our breath away.