I just waited for League to update for two hours and now it's doing it again?!?! [CLIENT]

Basically, I start up league as normal, watch it download everything (after waiting for ages because it decides to download at snail pace) then it gets to 33% and stops for two days, just stuck on it, nothing helped. After massive amounts of effort and through the power of deduction i finally made it work. I Get into the game, I accidentally log into the wrong account, so I log out, open league again and it says scanning files. Although it's stuck on 1 for about 30 minutes. I then close it and open as administrator, only for it to give me a crash report and start the download again from the beginning of step one (after having spent 30 minutes file scanning). AND YES, IT IS DOING THIS AT SNAIL PACE FOR NO REASON AGAIN.

So as you can see I am greatly confused, any insight or advice on the matter would be greatly appreciated. Thank you.