Sorry to hear that you got banned.

Are you sure it's the fault of SystemCheats? It's quite rare to see a ban case for GTA from us. Have you used mods previously or received money from modders online?
Still, I'm not saying it's impossible to be our fault but I personally play it with cheat & have past 200 hours already unless you're that unlucky to be reported. (I cheat hardcore, literally mass killing online users)