Just stop shooting when he deflects... Jeez. That shouldn't even be a problem. If you can't 1v1 Genji, the best way to get rid of him is to either chase him off or have your team help. Honestly, all of the other attackers can destroy him without breaking a sweat. As for your Mei problem, you must be doing it wrong. Use your wall more effectively and determine what fire mode should be used and when. As Mei, I never have a problem with Genji.