Shower not working for over 2 weeks, what are my options?

I moved into an older apartment that started flooding the apartment every time the shower was turned on. Eventually it got to a point where I couldn't use it at all.

I've had plumbers attend based on urgent repairs, but the issue is more complex than initially thought and a leak is also stemming from my apartment into the downstairs dwelling. They suspect a non-compliant plumbing installation and that rectification works may be required.

I needed to literally signup for a gym membership to go and shower there. The agent is being decent and said I'd get a full refund for the urgent repair work, but apparently the hold up is coming from the builder who is dragging their feet.

Is it possible to claim back some of my rental money on this property given that it's partially inhabitable in this state?