How do I get my fondant black?! I've tried everything and its always more if a really dark grey

It just takes a lot of black food coloring--which may change the consistency of your fondant, especially when just adding it to ready made fondant. If you do make your own fondant, you can add it when you mix in the liquid ingredients (although I'm not sure what the ingredients are since I have not made one from scratch).

Or you can just start using dark chocolate fondant and then tint it black, airbrush it or just get ready made black fondant.

Start with chocolate fondant. Uses less coloring and taste less bitter. Also when using dark colors let it sit for a day and the color will deepen.

Or you could buy black fondant.