Promos again and again Riot stacks the enemy team

Friendly tip: If you really want to climb in ranked, I recommend you to do the following things:

1. Don't waste energy on tantruming about irrelevant things such as teammates or Riot's matchmaking.

2. Realize you are probably not as good player as you think. Noticing and accepting your own flaws is the first (and only) step to improvement.

3. Play to win. Many players only want to maximize their KDAs/Damage dealt and they believe those factors alone will make them win. No. After all, League of Legends is still a strategy game, where every little action and decision matters. Good players think what they should do next in order to win the game instead of just staring at the scoreboard.

4. Learn the game. Tip number 3 requires a change of mindset but also a lot of game knowledge. It's essential to understand concepts like META, wave management, priority and how each role, champion and matchup works. Before the game even begins, you should come up with an ingame plan based on your analysis. Once the match gets rolling, every move you do should have a valid reason why you commit it. There are some fine guides on Youtube you can have a look at, such as Skillcapped or Pro Guides. They might help you on this matter.

5. Take your time. No-one gets superior skills instantly. Practise with the correct mindset, and you will learn and get better for sure.