They can only ruin your fun if you give them the power to do so, OP. The moment you claim someone else did something to... you have completely given them the power of emotion OVER YOU. You do that, not them.
Maybe just chillax a bit and don't take it so hard, man. It IS just a game for cripes sakes. Try to keep your dignity, calm and most importantly, your perspective from a position that YOU choose whether or not you're going to have fun at this and don't give your team or the opponents that power over you to claim they make you mad, ruin your fun or don't care enough to want to win like you do.
How do you know? That they failed at it is not proof of not caring or not trying. Some folks are so timid that they sit back and protect the arty -- and it's the BEST they can do under their benighted condition. Instead of railing about it and popping a vein or two, maybe laugh it off and on occasion, maybe send them a link to the forums where they can learn how to play without doing more than something like this:
"HI! I noticed you having a bit of trouble that last game. I'd like to offer you this so you can learn more about the game."
Then, if you wouldn't mind, send them a copy of this link via chat: The WoT Welcome Package (version 1). Of course, in chat, you'll have to copy the link address as the forum text link won't work in chat. And then follow up with something like:
"I hope you find it useful and if you do, please offer it to others. It's from the Official WoT Forums and you can go there to learn more, too! GL, HF!"
See how easy that is? And when you do that, honestly attempting to be kind, you might find yourself not as upset all the time.
Take back Control, OP, don't give others the power to ruin your fun.
I don't.
OvO