how to fix bathroom heat issue

TANYAC

I rent, and the bathroom is freezing. There is heat in the bathroom, but that's the problem its under the vanity sink. They have a 2 inch vent on it, just in the front, but there is no hot or even warm air even coming out. You can feel the heat from the inside the vanity on the base, but no were else. What is the best way to get the heat out into the bathroom, with out costing $$$.

HVACNUT

Pics?
Hot water or hot air heat?