Easy...just go to their profile (i think you can by selecting their name in the lobby and from there you will see like "View Combat Record" and theres "Report" and "Report Offensive Emblem" or "Name" but i would suggest to only Report. Haven't got banned yet but i never played rough or say anything bad (because i rarely use the mic)
Idk, but I did report two guys in Zombies, they've found a glitch, that is kinda like the one on Kino der Toten, you know the one in the first room. Abusing the AI of zombies
I reported them because it was some 8 yearld little kid and some teenager with mics, they were real jerks too, they closed the bus doors and left you to fight alone.
If they were'nt such **** heads I wouldn't have reported them because the glitch doesn't help you with the Tranzit mode, it is unfair though, but I'll be sure to report any cheater on the future.