If you're making plays and carrying, your team will respect you more and at that point if you tell them what to do, they'll do it. And since I'm usually the person carrying, if my team is going full retard getting caught out alone back to back, I usually just say something like "for the last fucking time, group 5 and stop getting caught out or I'm AFK". If your team doesn't want their 15-0 Sejuani to go AFK, then they'll start playing like they have a brain in their head and listen.
And trust me, I live up to my promises. Yesterday at the beginning of the game two players decided to spam pings on me because I didn't "move fast enough" ( minions hadn't even spawned yet and they were going apeshit about how long it took me to purchase items ). So after they pinged me 50 times, I typed "one more ping and I'm throwing this game", Lux decides to drop 15 more pings on me. We lost that game - I made sure of it. Gotta teach these autistic bastards some manners somehow, reporting isn't good enough. Gotta hit them where it really hurts.