Against that team, have all 3 members pick up a banshees, and make it winnable. Singed doesn't do a lot of damage lategame. He does *persistent* damage, and massive disruption. Midgame he's definitely a problem, and OP. Kill him early, or kill him late.
But your problem is you have 2 squishies and a semi-squishy (depending on how you built Elise). You're not going to be able to burst down any of those 3. And you can't handle the sustained damage they put out. If the 3 of them roam together, you lose all teamfights. So you'd better get good at picking them off, or defending and splitpushing.
They picked a strong TT team. You did not. You have your work cut out for you. Singed is already much weaker in s3 than he was in s2, especially on 5's. He won't be nerfed further, despite his strength on 3s.