So how do you get cheaters banned?

Just got out of a ranked 5's game. My team was quite ahead. We had all three of the opponents inhibitors destroyed. All of a sudden 3 members of our team are lagging uncontrollably and can't do anything. The other team was fine and 2 of our members were fine. It also was not my internet connection. I was in a Skype call with my friend who was also in the game. He even tried leaving and reconnecting to the game only to get the message "Unable to connect to server". It could not have been server trouble or both teams would be suffering from the lag. Also there is no way for me to know which one of them was responsible for the lag. I reported all 5 of them. Really annoyed that this could happen. Never had any problems like this before. Our easy win turned into a loss. Like. What the fuck?