Republicans have been railing against the Affordable Care Act since before it even passed, John Oliver noted on Sunday's Last Week Tonight. But now that Republicans control Congress and the White House, they can't just gripe about ObamaCare — and in fact, "all week long, Republicans have been dealing with an unexpected problem: constituents at town halls furious that ObamaCare might be taken away." "So tonight, let's look at ObamaCare: what it does, what needs fixing, and how Republicans plan to replace it," Oliver said, and he started off by taking everyone back to "just how bad things were before it was passed." ObamaCare fixed some of the systemic problems — getting rid of coverage denial for pre-existing conditions, allowing children to stay on their parents' plans until age 26.