Ya this really isnt making any sense. If what im reading correctly, you state that someone gave you "hacked" accounts and you played with them. Now you got ban and for some reason IP ban as well. Have you guys tried making new accounts, or are you guys just trying to access these accounts? Like i said this doesnt make sense because Riot as far as i know doesnt do IP bans for this exact reason. Let alone if something like this was to happen whats stopping someone from doing this at say a Dorm, or Internet Cafe? If anything who actually pays for the internet, maybe they blocked you guys out of it, or maybe there is something wrong with your ISP. Try and contact them, or have the person who pays for the internet contact them.
The last thing i want to state is that just because you dont know you are breaking the rules doesnt give you a free pass to break them. Let alone Riot doesnt need to give you a warning especially on something as common as this. it would be like killing someone and stating in your defense that you didnt know they would die, or robbing someone and you didnt know that was a bad thing. Its just common sense. Making an account on here is easy and free. why you needed how ever many accounts you needed is a red flag itself. All im trying to say is that you broke the rules. You can claim all you want that you didnt know it was bad, you still did it and because of that Riot decided to take action. its sad that other people's account needed to get involved, but that is what happens when someone breaks the rules. Maybe next time you can just make one account and keep that, dont use other accounts especially ones in which you didnt create!