It feels like you are being treated unfairly, but there is a problem with your perception. The people who seem to be getting a free ride are working under similar burdens. The difference is they have been suffering in silence. Before jumping to conclusions, have some private conversations. You'll quickly learn that what seemed to be a personal problem is a dilemma that is undermining the entire organisation. Once you understand the true scope of this disaster, you'll be able to take effective action.