Help! Supporting Gold / Plat players with tanked MMRs!

I'm ending up supporting Gold/Plat players with (I assume) tanked MMR (because they're randomly in a bronze/silver game)

Here's the issue: I don't know what the heck they're thinking. They're aggressive, they go in on cues no-one on my team can recognise, they expect things I don't know the name of. They think they're going to shoot fish in a barrel, they think their only option is to make huge plays to solo-carry the game. They feed practically every time. They blame the support.

I've tried going ham for them (Leona main, so not a problem) but if we get behind? I stop, and they keep feeding. If I don't go ham, they'll do it out of frustration. I've tried Sona (my third main), but her Q is an engage now. I've actively reminded them I'm a bronze player and am not in the same headspace or mechanical skill level as them--- it's just ignored ( a good gold/plat doesn't need to be told this! They just adapt! ) My pings and map awareness don't exist to these players...

Losing games wouldn't bother me but, turns out Gold/Plat ADCs with tanked MMRs in soloQ are unholy levels of toxic. So I get verbally assaulted for 40 minutes. Which means I'm only playing support when I can handle that. Help is mega-appreciated. I'll take picks- positioning- tactics, Jedi Mind Tricks- anything >_<