Instead of harsh chemicals or a plunger, try 1/2 cup of Dawn dishwashing detergent! Just pour it right in the clog and let it sit. After 30 minutes, try and flush. If you don't have Dawn, any detergent brand name will work.
I was helping my friend clean a bathroom that had a clogged basin drain. After the two of us polished off half a two-liter bottle of diet pop, I filled it with water, matched the opening of the bottle to the drain opening and mashed the bottle firmly.
There's no way to afford a new tub right now. Does anyone know how to repair a plastic bathtub? I have a garden tub and the seat is cracked to the point that unless I keep duct tape (the only thing to stay on more than a few days so far) over the crack, the tub leaks horribly.