Rank MMR discrepancy

Ive notice a major issue whenever I decide to play rank with a duo partner who is either gold 4-5 while im silver 1. The issue being the two teams total mmr discrepancy. The opposing team has had a + 100 mmr advantage difference. Instead of averaging the mmr between my duo partner in myself it puts us a much higher opponent bracket. My team would consist primarily of gold 4-5 while the other team would be gold 1-2 and sometimes even plat 5. Furthermore, my teammate have been tilting in the majority of their previous games.

Now I am a rager and have amassed a large sum of chat restriction, but my winratio in rank game is 55% and my champions all have 55% win rate with a k/d/a of +3.2 as a support main. Yet my teammate have a total rank win ratio of 44% or below. Yet they are still in gold 4-5 and im stuck in silver 1. So what is wrong. Is the game selectively putting me with these people bc of my conduct as opposed to player who never rage or troll and have +50% win ratio. As a support its frustrating. I can win my lanes. But the moment laning phase is over, my adc begins to feed bc he over extends while I ward. Also I am the only one warding and the team qq about not having enough wards on the map. Its frustrating to go 2/0/6 in the laning phase to lose the game completely bc of these trolls. WHo refuse to ward, refuse to pay attention to warnings or calls, refuse to look at the mini map and just tunnel vision.

Im not say im the best, I am far from it, but i learn from my mistake and try not to repeat them. I have also notice I am the only one who carries around a pink ward when facing twitch rengar eve or akali. My teammates never buy them. WHat can I do to stop having such teammate. Isnt duoing support to help?