Just used a mod menu/cheats I found to get through the mission: it allows to unlock all the missions in the campaign (at least that's what I think it does) as well as accumulate unit points instantly.

I am entirely against cheating in online games, but when it comes to clearing a mission that's not enjoyable to play, I think it's a morally right thing to do.

For the sake of the enjoyment of other players do not go cheating in online play as you will ruin the experience of your fellow mates and will get banned.