Many Overwatch players feel helpless once a Mei character uses an Ice Wall exploit in the 3v3 mode. There are ways though, to counter this cheat move.

Mei's Ice Wall Glitch

It seems Mei can use her Ice Wall to go at the very edge of the map. Unfortunately, this gives her the advantage of shooting down her enemies who can't retaliate. The cheaters' favorite spot is Ecopoint: Antarctica during 3v3 mode. There's a ceiling there that Mei and the rest of her team can hang out. A lot of Overwatch players have been complaining to Blizzard about it. So far, the issue has yet to be resolved.

Counter Strategies Vs Mei

One Reddit user posted several suggestions on how to counter this Mei cheat trick. One way is to exploit the same method by having one Mei as a teammate. This ally can race the opponent to the outside spot and try to kill them in the process. Another way is to kill the enemy Mei as soon as possible before she can use the exploit.

Lure Or Bore Them Down

Overwatch players can also try to draw out Mei from her safe place. You could lure Mei out by pretending to you are AFK. Just put your character in a safe but visible spot and don't move. This will convince Mei that you are an easy target. Once she gets down, you can move in for the kill.

If you are not that patient, then simply leave them alone and do something else in the map. If they don't want to come out and play them neither will you. Eventually they might come down and fight or hopefully fall off the map. Some of the other counter strategies sound good but these are the most practical ones. Ultimately, only Blizzard can put a stop to this Ice wall exploit.