What to do about a water leak mgmt won't fix?

I just moved in to a new apartment a few months ago. When I realizes a leak coming from underneath the base board of the sink. We have had the water heater replaced and the fridge is fine. I spoke with management multiple times and they keep tellin me they with fix the problem. It's been 3 months and still no solution has been give and the problem has not been addressed recently.i am worried because the smell is horrific. Smells like sewage. Embarrassed to have company. And afraid of black mold possibly.What can I do to fix this issue?