For Riot Games: You owe me a promotion

As I'm writing this thread, I'm just a few clicks away of uninstalling League of Legends from my computer, forever. The only reason why I haven't rage quit and thrown my PC off the balcony yet, is because of the (hopefully positive) respond I'll recieve from an admin of some sort, who can help me.

I have an old PC with a lot of issues, which has resulted in my PC randomly freezing or restarting. Unfortunately, most of these incidents were during ranked games. This has now led to me getting a low priority queue ban on 20 minutes for 5 games... 3 times over 1 week.

I get that your system is only trying to punish those who leaves the matches, resulting in the team losing, a frankly a shit time for the rest of the team mates - makes sense. But here is my issue with it: The first 2 low priority queue bans made me factory reset my entire PC, to make sure it would never happen again as I was playing League of Legends. But in my last game, which was the final match I needed to advance in my promotion series from Bronze III to Bronze II (which is a lot for me), my PC froze for the first time since the factory reset, causing me to restart my PC and not participating in the game for 3-5 minutes.

When I got back on, my team was still leading - to be honest me and my friend from premade managed to carry the entire team to victory. And as I thought I was about to get the win and rank up, I'm met with the "Leaverbuster" notice on my screen. Which means that I now not only have ANOTHER low priority queue ban on 20 minutes for 5 games, but I didn't get the win either (as you don't get LP for winning a game when you've disconnected for some reason). So now I'm back to 67 LP and have to get back up to 100 LP to get my promotion series and then finally win the last match so I can rank up, whilst being in low priority queue (fun).

What I am very annoyed with in this situation, is that I didn't get the win and didn't rank up, despite doing really well in the match and winning the game, although being disconnected for 3-5 minutes.

Is there some way to rid me of this low priority queue or perhaps even give me the division rank up I was supposed to get? If not, then I unfortunately have to let you know that you have lost a very big fan of the game.