I've failed 4 promos in a row while having a 65% win rate in ranked. What can I do to improve?

I have just failed my 4th promo in a row. I'm 0/9 in these promo games while I have a 65% solo/duo ranked win rate over the past week. This includes all the promos I failed.

In this promo:

The first game the top lane fed to the tune of 0/9/0 and the support dc'd halfway though the game. We surrendered in 23 minutes. https://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/2715161651/243611839?tab=overview

The second game the rest of the team combined for 4/17 while I went 6/4. We surrendered in 21 minutes. https://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/2715187873/243611839?tab=overview

My first question is could I have carried these games? What should I be doing differently? Are there any tips or what to do's when a lane is feeding and the others go even at best? is it a possibility that myself as a relatively new player could have won?

The second question is are promos like this for everyone or am I just having terrible luck? It seems like every game someone either feeds or disconnects. Is this just a Bronze thing and I just have to struggle through or are there things I can do to improve my chances at winning a promo?

I started playing this game about the start of the new season. I'm about ready to quit. It seems pointless to keep playing when I get consistently terrible teams, and will never improve my rank.

How do I prevent this from happening?