Could you guys give some advice?

After a year of playing League i played my first 10 ranked game and with a terrible 2 - 8 rcord i was placed in bronze 2. There were games when i was stupid enough to play with guys whom i had known to be ragers and flamers and lost the game. There was a game where my intenet connection dropped. And there were games where i was crap. I completely understand how it was mostly my fault that i have lost these games. Well except for the internet i dont have control of the quality of the connection but mostly it's quite perfect. And i learned the leson about choosing teammates too. Also i am trying my best every game. But there is a certain kind of game i am running across quite often now. There were a few in my placement matches and the last few ranked games i had this experience as well. Where 1 or 2 teammates seemingly play another match. And i cannot find a way to do anything about it. A few examples:

• After a good start and a few dragons Amumu decides to go in solo against 4 enemies and dies. When we ask him not to he proceeds to do it 5 more times. He does this when the team is not around so we cannot se this as a baut into a favourable teamfight. So guy continues soloing starts flaming us for not helping him (best case scenario would be a 3v5) and we lose the game as we need to et back into a defensive state.
• Diana decides she needs to push because kills are not important as much as turrets. She is right although she always does this when we the team has the opportunity to push at mid together. So we cannot push mid without her we are weak enough for the enemy to keep us at bay. Now what the team wants to do is to push mid in which would be do-able 5v5. We are not chasing kills. We need her but she goes off to push lanes that would take forever to actually benefit from when we could just straight up go in mid. It would be a good idea to take other lanes to the inhibitor as well but it would be so much easier with the enemy needing to defend their iner turrets from the siege minions at mid. Miraculously we have won that game with an incredibly hard 4v5 fight. When the enemy nexus died Diana was pushing the second turret at top from the inhibitor.
• I'm playing Vladimir mid against a Katarina That plays fairly well. I manage to keep her away from farm and kiling me. She decides to go roam goes top. The whole team is pinging our Xin Zhao as he proceeds to run into a 2v1 against a full hp katarina and a Shen. The brush where she was hiding was warded all the time. Xin saw her and then decided to go in with Shen in his ass. Next thing i see in the chat is REPORT VLADIMIR!!! Then she got fed of course every fight she oblitarated us and i just couldnt understand. I went all in on her poked her when she was not jumping in yet, and when she did i ulted ignited qed ed went down into pool but that wasn't enough. Xin and our Warwick was constantly focusing Shen. When Kata ulted They attacked Shen. Or Braum. Both were tanky as hell. I asked them multiple times to help the rest of the team to take out the big damage squishies katarina and Nidalee bt these guys didn't react. And this is what i see the most. When some squishy ass snowbally champ gets fed you have to be really lucky to have the team focus or silence that champ. Or just somehow deal with that champion first. I have so many teamfights when lots of guys go all in on a maokai or a shen or some tanky ass champ that is nearly impossible to kill before we all get torn apart by the enemy carry or the Kata like wonderful champs.

So my question is: What could i do in these situations? When 1 or 2 guys are completely refusing to understand what i am asking or trying to explain. What could i do? When someone just goes against the majority of the team and decides to fuck it all u with some epic 1v4s? When some guys cannot get their cursor off the 4000 HP Braum when the 12/4 Kata is utling next to them?

What could i do? I can't 'carry harder' this is a team game. I need these guys just as much as they need me. But when they don't understand simple sentences what can i do?